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Gem Exploration Using a Camera Drone and Geospatial Analysis: A Case Study of Peridot Exploration in British Columbia, Canada


Abstract and Figures

Consumer-grade camera drones have dramatically improved with regards to affordable cost, camera quality, telemetry capabilities, flight time, and location data. This case study examines the use of a drone camera and geospatial analysis in peridot exploration. Gem-quality olivine (peridot) occurs in peridotite xenoliths in the Chilcotin Group Basalts (CGB) of central British Columbia. Geospatial analysis and satellite image verification identified 73 CGB outcrops in the southern Monashee mountains near Kelowna and Vernon. Qualitative peridotite xenolith remote detection was successful at a chosen test site. At 15 m above ground level, the ground sampling distance is approximately 5 mm/px, thus more than sufficient to locate xenoliths (~5-15 cm) in visible spectrum images. A DJI Mavic Pro drone and HD first person view goggles were used to assess 15 localities for peridot potential. Only 6/15 localities contain peridotite xenoliths, and at concentrations (1-2 vol. %) far below that of peridot gem mines (30-50 vol. %). Use of a drone saved considerable time in the field. The combined GIS-UAV approach could be used to facilitate peridot exploration in a large area in central BC. Camera drone remote exploration could be used for other types of gem deposits, notably lapis lazuli and pegmatite-hosted deposits. (Journal of Gemmology volume 37, p 80-90)
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Gem Exploration Using a
Camera Drone and Geospatial
Analysis: A Case Study
of Peridot Exploration in
British Columbia, Canada
Philippe Maxime Belley, Pattie Shang and Donald John Lake
ABSTRACT: This case study examines the use of a consumer-grade unmanned aerial vehicle (UAV,
or drone) and geospatial analysis for peridot exploration. Gem-quality olivine occurs in peridotite
xenoliths hosted by Chilcotin Group basalts in south-central British Columbia, Canada. Geographic
information system (GIS) geospatial analysis and satellite image verification identified 73 exploration
targets consisting of basalt outcrops and talus slopes in the southern Monashee Mountains near the
cities of Kelowna and Vernon. A DJI Mavic Pro drone was used in conjunction with high-definition
(HD) first-person-view goggles to assess 15 localities for peridot potential. Six of them contained
peridotite xenoliths, but at concentrations (1–2 vol.%) far below that of economically viable peridot
deposits (30–50 vol.%). The use of the drone saved considerable time in the field, and the combined
GIS-UAV approach could be applied in the future to facilitate peridot exploration throughout a large
area of central British Columbia. Camera-drone remote exploration could also be applied to other
types of gem deposits, such as lapis lazuli and those hosted by granitic pegmatites.
The Journal of Gemmology, 37(1), 2020, pp. 80–90,
© 2020 Gem-A (The Gemmological Association of Great Britain)
Recent technological advances have signifi-
cantly improved the range, flight time and
camera quality of consumer-grade UAVs, and
mass production has made them consider-
ably more affordable. These improvements have made
camera drones feasible, cost effective and potentially
useful for the exploration and field reconnaissance of
gem and mineral deposits. More-sophisticated drones
capable of conducting hyperspectral imaging, aerial
magnetic and photogrammetric surveys are already
being employed in mining and exploration for various
commodities (e.g. Kirsch et al. 2018; Jackisch et al.
2019). We present a case study demonstrating the use
of GIS geospatial analysis combined with observations
made with a camera drone and on-site in conjunction
with basic exploration criteria to efficiently explore for
basalt-hosted gem-quality peridot (e.g. Figures 1 and 2)
in British Columbia (BC), Canada.
Production of peridot gems from BC has been sporadic
and occasional, being primarily extracted by hobbyist
collectors. The first record of peridot in BC was published
by Galloway (1918), who noted that a prospector sent a
number of stones from Timothy Mountain (also called
Takomkane Mountain; Wilson 2014) to Tiffany & Co.
for examination, but that they were too flawed to have
significant value as a gem material. What is perhaps the
most well-known peridot locality in BC, Lightning Peak,
was first reported in a guidebook for mineral collectors
by Sabina (1964). Several peridot occurrences have since
been discovered (Wilson 2014; present article), and they
have produced small amounts of rough material that
yielded several dozen faceted stones weighing >1 ct. The
largest peridot gems reported from the region weigh over
4 ct (or 3.52 ct for Lightning Peak specifically; Wilson
2014). Overall, gem-quality peridot is rare relative to the
total amount of olivine present, since most xenoliths
are generally too fine grained to yield facetable material
(Wilson 2014).
Gem-quality peridot (Fe-bearing forsterite olivine) is
primarily produced from two types of host rocks. In
the first type, peridot typically forms euhedral crystals
in open cavities or in talc/serpentine within peridotites
or coarse-grained olivine dykes cutting peridotite (e.g.
Figure 1: This basalt-hosted peridotite xenolith was found during field exploration in British Columbia, Canada. Several fragments
of gem-quality peridot are visible on the surface of the broken xenolith, which is approximately 15 cm long. Photo by P. M. Belley.
Figure 2: The peridot in the
xenolith shown in Figure 1
was faceted into numerous
gemstones. The gems in this
selection weigh up to 1.65 ct.
Photo by P. M. Belley.
Egypt, Kurat et al. 1993; Myanmar, Kammerling et al.
1994; and Pakistan, Qasim Jan & Asif Khan 1996). In the
second type, peridot occurs as crystalline aggregates in
peridotite xenoliths that are hosted by alkali basalt (e.g.
western Canada, Wilson 2014; China and North Korea,
Koivula & Fryer 1986 and Zhang et al. 2019; Italy, Adamo
et al. 2009; USA, Koivula 1981 and Fuhrbach 1992; and
Vietnam, Thuyet et al. 2016).
In Canada, gem-quality peridot occurs within perid-
otite xenoliths in the Chilcotin Group basalts (CGB) of
south-central British Columbia (Figure 3). The CGB are
spread relatively thinly (averaging 70 m thick; Dostal
et al. 1996) over an area of 25,000 km2 in the inter-
montane super-terrane of central and southern BC
(again, see Figure 3; Dostal et al. 1996; Dohaney 2009).
The basalts erupted from 24 to 0.74 million years ago
(Dostal et al. 1996 and references therein). They overlay
various rock types, including Proterozoic orthogneiss,
Devonian–Triassic basalt of the Nicola Group, Carbon-
iferous–Permian greenschist, Jurassic granite, the
Cretaceous Okanagan batholith, and Eocene volcanic
rocks of the Kamloops and Penticton Groups (see Massey
et al. 2005). Bevier (1983) concluded that the CGB were
generated in a back-arc tectonic setting, possibly due to
upwelling of the asthenosphere, in addition to possible
influence from a mantle hot spot. The peridotite xenoliths
(classified petrographically as primarily spinel lherzolite)
were transported from the upper mantle to the earth’s
Figure 3: The study area is situated in south-central British Columbia, Canada, near the cities of Kelowna and Vernon.
The distribution of Chilcotin Group basalts is shown in yellow-green. After Dohaney (2009); used with permission.
0 50 100 km
Study area
surface by the basaltic magma, which itself originated
due to partial melting of upper mantle rocks. Only some
flows contain peridotite xenoliths (e.g. Fujii & Scarfe
1982). The composition of olivine in the xenoliths from
one locality in the study area was reported in the range
of 87–92 mol.% forsterite (Fujii & Scarfe 1982).
The distribution and elevation of basalt exposures
was influenced by the paleotopography (pre-existing
hills and valleys) at the time of volcanism, with some
flows having a 400 m difference in elevation (Mathews
1988). The landscape and rock outcrops were physi-
cally transformed by glacial erosion in the Pleistocene
(Nasmith 1962) and subsequent erosion from freeze-
thaw and gravitational forces, resulting in the formation
of rock talus (e.g. Figure 4) below steep basalt outcrops.
Description of the Study Area
The study area is situated in the southern portion of the
Monashee Mountains, just east of the cities of Kelowna
and Vernon. It was selected because it is known to
contain peridot and is in closest proximity to the authors’
location in Vancouver. The elevation ranges between
1,200 and 2,140 m above sea level, and the region largely
consists of hills and valleys covered primarily by conif-
erous forests (Figure 4). Active logging is ongoing and,
as a result, gravel roads are locally present in the region.
Talus can be present in steeper areas, especially along
the sides of valleys. The challenging terrain, expansive
forests and sparse roads make fieldwork in this area
time consuming. The forests are home to numerous
animals, including deer, moose, elk, cougars, wolver-
ines, black bears and grizzly bears. Moose, deer and
both species of bear were seen on several occasions
during the authors’ fieldwork.
Exploration Criteria
Commercially significant basalt-hosted peridot deposits
contain a high content of peridotite xenoliths: 30–50
vol.% at San Carlos, Arizona, USA (Vuich & Moore 1977)
and Jilin, China (Wang 2017). Since only a small portion
of peridotite xenoliths contain gem-quality material, and
due to the gem’s relatively low per-carat value, a high
concentration of peridotite xenoliths is a key factor in
the economic feasibility of a deposit.
Basalt containing about 5% or more of peridotite by
volume will appear noticeably different when observed
from a short distance in the field, which the authors
confirmed in a camera-drone feasibility test (described
below). Peridotite xenoliths can be identified in photo-
graphs and videos by their yellowish green colour and
their blocky/subangular shapes within the dark basaltic
matrix. For more effective exploration, the basalt needs
to be well-exposed. Furthermore, the locality must be
relatively accessible, since mining costs can become
prohibitive in remote areas.
Therefore, the exploration criteria for basalt-hosted
peridot can be summarised as: (1) occurrence of a basalt
unit known to contain peridotite xenoliths, (2) good
physical exposure of the rock unit, (3) relative ease of
access and (4) high concentrations of peridotite within
the basalt.
Geospatial Analysis
The first three exploration criteria mentioned above
were employed to locate potential targets within the
study area. Government of British Columbia data were
used together with ESRI ArcGIS software to identify
Figure 4: This view looking
west from the basalt talus
at Lightning Peak shows the
typical terrain of the southern
Monashee Mountains, where
active logging takes place. See
person for scale. Photo by
P. M. Belley.
exploration targets in the region. Several well-exposed
examples of basalt-bearing talus in the study area have
slopes equal to or greater than 30°, so slopes of such
steepness were used to target talus for exploration. Slope
was determined using the BC digital elevation model
(0.75 arcsec x-y resolution, or 20–30 m). Locations of
interest were determined by having the following condi-
tions: (1) slope 30°, (2) bedrock geology consisting of
CGB and (3) less than 10 km proximity to major roads or
less than 2 km from local or logging roads. Exploration
targets were then selected using Google Earth satellite
imagery to filter out false positives, such as where a
steep slope occurred in unconsolidated glacial sediment
which, in areas, covers the older bedrock.
Camera Drone Exploration
Concentrations of peridotite within the basalt were
evaluated using a DJI Mavic Pro drone (Figure 5), which
weighs 734 g, has a maximum speed of 65 km/h, an
overall flight time of 21 minutes (27 minutes maximum),
a maximum transmission distance of 7 km (under ideal
conditions), a GPS receiver and a 12.35 megapixel
(effective pixels) 4K video camera. The device commu-
nicates with a radio controller and supplies a live HD
video feed to the user via a smartphone or DJI Goggles.
The latter are first-person-view flight goggles that receive
data from and communicate with the drone in real time,
which allowed us to see in far greater detail than through
a smartphone app or external screen. This proved useful
for rapidly assessing exploration targets as well as piloting
the aircraft in close proximity to rocky outcrops and trees.
However, a spotter was required when using the goggles
both for legal purposes and to watch for bears.
The camera includes a 1/2.3-inch CMOS (comple-
mentary metal-oxide semiconductor) sensor and a lens
with 5 mm focal length, field of view of 78.8º, f/2.2,
distortion <1.5% and focus from 0.5 m to infinity. The
maximum image size is 4,000 × 3,000 pixels. At 15 m
flight elevation, the ground-sampling distance—the
actual length of ground captured per pixel—is 0.46 cm/
pixel. Although error is introduced by uneven surface
topography, lens distortion, movement during capture,
inaccuracy of height measurements above ground level
and other factors, the ground-sampling distance is well
below the expected xenolith size (e.g. commonly 5–15
cm at the San Carlos, Arizona deposit: Vuich & Moore
1977; typically 1–20 cm in Chilcotin Group basalts:
Fujii & Scarfe 1982 and Wilson 2014) at distances from
exposures achievable by the DJI Mavic Pro in talus (4–15
m), so the xenoliths should be clearly visible under
ideal conditions. Xenoliths were identified remotely by
visually inspecting photographs and live video feeds.
The presence of yellow lichen, which is common at
Lightning Peak, can obscure xenoliths. The xenoliths are
differentiated upon closer examination of photographs
by their green colour and subangular shape. While a
quantitative, automated method of xenolith detection
could be developed, the qualitative inspection of images
required no complex development, minimal training and
was extremely cost effective.
Geospatial analysis with ArcGIS yielded 73 exploration
targets in the study area (Figure 6). False positives were
rare, and typically occurred in creek or river valleys
that steeply cut through a top layer of unconsolidated
sediment. At least four false negatives (where CGB
outcrops were not successfully identified with geospa-
tial analysis) were either found during fieldwork or seen
in satellite images near identified targets. They tended
to be in flatter areas that contain smaller talus slopes.
The camera drone was first tested at a location known
to contain peridotite xenoliths in basalt: Lightning Peak
(2,139 m elevation). At the time (4 June 2017) the
locality was not readily accessible due to snow, so the
drone was flown from a point more than 2 km away
(Figure 7). Basalt blocks at Lightning Peak contain 3–5
vol.% peridotite (visually estimated from a previously
done on-foot traverse across the talus). Yellowish green
peridotite xenoliths were successfully resolved by the
drone camera hovering approximately 17 m above the
talus with the camera pointing straight down (Figure 8).
The drone was then used to evaluate exploration
targets in other areas that ranged from 0.2 to 2.1 km away
Figure 5: The DJI Mavic Pro foldable quadcopter
camera drone was used for this study. It measures
33.5 cm diagonally (propellers excluded) and
weighs 734 g. Photo courtesy of DJI.
by air from the nearest road access point (e.g. Figure 9),
with single-flight paths reaching 4.35 km in total distance.
Fieldwork consisted of a total of six days in late spring
and summer of 2017–2019, during which 16 targets
were examined (three of which were false negatives).
Excluding the previously mentioned Lightning Peak
locality, six of the targets contained peridotite xenoliths
and gem-quality peridot, while the other nine did not
contain peridotite (again, see Figure 6). We found that
peridotite xenoliths are more difficult to resolve with the
drone at lower-elevation localities (e.g. at about 1,350 m)
because the rocks have significantly more lichen cover
than at higher elevations (e.g. at Lightning Peak), and
because the peridotite at lower elevations is usually signif-
icantly more weathered. In basalt blocks that have been
extensively exposed to the elements, xenoliths can be
completely weathered out (Figure 10a). Xenoliths in basalt
from more recent talus may show brownish surficial
weathering (Figure 10b), while rare, very recent rock
slides may expose fresh peridotite (Figure 1). Xenoliths in
all stages of weathering were identified in drone images.
A low abundance of peridotite xenoliths typified all
six targets (about 1–2 vol.% as confirmed by in-person
visual estimation, compared to about 3–5 vol.% at
Lightning Peak). Approximately 1–2% of the xenoliths
contained facetable material (expected finished weight
>0.5 ct). The cluster of localities in the southern part of
the study area (again, see Figure 6) contained sparse,
coarse-grained olivine crystals (2–5 cm) within peridotite
xenoliths, but these crystals were generally non-trans-
parent (the largest transparent stone faceted from this
material weighed 1 ct). In the northernmost cluster of
Figure 6: Exploration target results from geospatial analysis of Chilcotin Group basalt exposures in the study area are shown
together with proximity to roads (yellow lines). Camera-drone exploration of some of these localities indicated those that were
barren of peridotite xenoliths, as well as those containing peridotite xenoliths. Also shown are a few false negatives (i.e. those
not identified via the ArcGIS analysis), as well as unexplored exposures. Satellite imagery from Landsat/Google Earth.
(false neg.)
Barren (false neg.)
Chilcotin Group basalt
0 10 km
peridot-bearing localities, we found a few xenoliths
containing gem-quality material. At one of these locali-
ties, a recent slide exposed a very large xenolith (originally
about 30 × 20 × 20 cm) that broke into five pieces (e.g.
Figure 1), which we found loose and within basalt blocks
on the surface of the talus during an in-person traverse.
Faceting of rough material from this xenolith produced
22 carats of commercial-grade cut stones weighing
0.80–1.65 ct (Figure 2), but this occurrence produced
no significant gem material outside of this find.
A small portion of the xenoliths consisted of pyrox-
enite with very minor or no olivine. At one locality,
gemmy dark green pyroxene xenocrysts up to 2 cm
across occurred in low concentrations within basalt
that was devoid of peridotite xenoliths. The pyroxene
xenocrysts were observed in person and were too small
to be identified in drone images.
Suitability of Geospatial Analysis
While geological maps could be cross-referenced to
satellite images manually to locate exposures of Chilcotin
Group basalt, the process is very time consuming.
Geospatial analysis using ArcGIS proved extremely
effective at identifying these exposures in a large-scale,
automated fashion in minimal time. This process may
immensely facilitate the identification of CGB outcrops
over a 500 × 250 km region of central BC to the north-
west of the study area. Satellite images also proved very
useful both to confirm the occurrence of CGB talus and
to plan navigation on logging roads. False negatives
(where CGB outcrops were not successfully identified)
occurred in more flat-lying areas, so geospatial analysis
is most accurate in steep terrain.
Figure 7: The flight path for the Lightning Peak test run is
shown as yellow lines, in both top (a) and side (b) views. An
enlarged side view (c) depicts the flight path over the talus
slope on the western side of Lightning Peak. The ‘home’
(take-off) point is at an elevation of 1,766 m above sea level,
and the top of Lightning Peak is at 2,139 m. The lowest part
of the talus is at 2,050 m. Satellite imagery and terrain from
Landsat/Google Earth; flight data processed by
Figure 8: (a) This drone photograph of basalt talus at Lightning Peak (elevation 2,083 m) was taken from approximately 17 m
above ground level. (b) A close-up of the upper left portion of (a) shows peridotite xenoliths (circled) in blocks of basalt. The
locality could not be accessed by foot due to an abundance of snow, but snow-free parts of the talus could nonetheless be
inspected with the drone. Photo taken 5 June 2017 with the camera oriented straight down (–90°) towards the ground.
Figure 9: An example flight path for a peridot target (here, barren basalt) is shown as yellow lines, in both top (a) and side (b)
views. The ‘home’ (take-off) point is at an elevation of 1,407 m and the top of the basalt cliff is at approximately 1,550 m. Satellite
imagery and terrain from Landsat/Google Earth; flight data processed by
~ 0.5 m
Camera Drone Exploration:
Benefits and Limitations
Using the drone camera in the field saved considerable
time and effort, since verifying targets remotely is signif-
icantly faster and easier than inspecting them in person.
In addition, the telemetric and sensor capabilities of
modern consumer-grade camera drones such as the DJI
Mavic Pro make it possible to determine an approximate
ground-sampling distance using altitude data; however,
there is room for improvement. For one trip, we estimate
that our three days of work would have taken two weeks
with traditional prospecting (much time is lost setting up
and taking down camp, and fewer sites can be verified in
a day via hiking). The HD first-person-view goggles were
useful for immediately assessing peridotite abundance,
the alternative being the post-flight examination of
photographs and video footage. More importantly, the
goggles give a much clearer live view than a smart-
phone, which helped avoid obstacles (e.g. trees and
branches) during the final approach. One limitation of
the drone is that forest can sometimes obstruct commu-
nication with the drone, making a close approach to the
talus (<15 m above surface) problematic due to diffi-
culties in maintaining the live video feed. Since a close
approach to talus is necessary for proper assessment,
the exposure must be within (or close to being in) the
line of sight. Vertical basalt exposures above talus were
sufficiently above the tree line to enable target assess-
ment in forested areas.
The presence of peridotite xenoliths in basalt—
even at low concentrations (3–5 vol.%)—was easy to
detect visually from images taken at approximately
15 m above ground level. However, some conditions
make peridotite detection difficult: (1) weathering at
lower elevations (about 1,350 m; causing round-shaped
holes in the basalt that correspond to the locations of
former peridotite xenoliths or a brownish appearance of
less-weathered xenoliths; see Figure 10), (2) excessive
lichen cover (more common at lower elevations and
probably also on south-facing slopes) and (3) low
peridotite concentrations. Nevertheless, it is probable
that a viable peridot deposit (containing 30–50 vol.%
peridotite in basalt) would be evident in drone-camera
footage even under these conditions. Despite the effects
of weathering, the presence of peridotite xenoliths was
successfully detected from drone images. However, our
field observations expanded the exploration criteria from
locating only green subangular inclusions in basalt to
include light brown weathered peridotite and holes left
by the complete weathering of peridotite. It should be
noted that open cavities or large vesicles in basalt could
be mistaken for weathered xenoliths, although no such
instances were observed during our fieldwork.
Assessment of Peridot Potential
in the Kelowna Area
While the CGB in the Kelowna area of British Columbia
has produced good-quality, albeit relatively small, peridot
gemstones (e.g. Figure 11), the source material (perid-
otite xenoliths) was absent from more than half of the
localities we examined. Even when present, the concen-
tration of peridotite xenoliths (generally 1–2 vol.% and
up to 5%) in the CGB is far below that at commercially
mined deposits (30–50 vol.% at San Carlos, Arizona, and
Jilin, China; Vuich & Moore 1977 and Wang 2017, respec-
tively). Despite this, much of the CGB remains unexplored
Figure 10: These two close-ups of the talus at a locality in
the northernmost cluster of peridot occurrences (elevation
approximately 1,350 m) show (a) holes resulting from
the weathering of peridotite xenoliths and (b) weakly
weathered brownish peridotite xenoliths in a boulder from a
more recent rock fall. The weathering-out of the peridotite
shown in photo (a) is not common at higher elevations (e.g.
Lightning Peak). The camera was oriented straight down
(–90°) towards the ground.
~0.5 m
for gem-quality peridot. Many more exploration targets
identified during this study remain to be examined, and
the potential for commercially viable peridot deposits
may exist elsewhere in the CGB, which covers an area
of 25,000 km2 in south-central BC (Dostal et al. 1996).
Potential also exists in other basalt units of the region,
such as the Endako Group (Brearley et al. 1984).
Application to Other Gem Deposit Types
Qualitative camera-drone exploration is suitable for any
deposit that features colours or textures easily recognis-
able from a distance, and the technique significantly
increases productivity—particularly in steep terrain.
Examples of gem deposits that might be prospected
using camera drones include: (a) lapis lazuli, which is
bright blue and requires large quantities to be economi-
cally viable for mining; and (b) granitic pegmatite dykes,
which may be visible cross-cutting country rocks in
mountainous terrain or exposed due to a relative lack
of weathering. Qualitative visual examination of drone
video/images is likely insufficient to detect gem deposits
with a less characteristic appearance when observed
from a distance. UAV exploration is most effective in
areas with good surficial rock exposure, such as in polar
regions (e.g. as suggested by Belley & Groat 2020) and
in arid and alpine climates.
Geospatial analysis combined with the use of a
camera drone dramatically improved the time and cost
efficiency of exploring for peridot deposits in the CGB of
south-central British Columbia. Peridotite xenoliths were
resolved by the drone at an altitude of approximately
17 m, even at low concentrations (3–5 vol.%), but they
were more difficult to observe at localities where weath-
ering and lichen growth were more intense. However,
these challenges are not expected to interfere with the
remote detection of an important peridot gem deposit
(i.e. basalt containing about 30–50 vol.% peridotite).
Known peridot occurrences in the study area contained
low peridotite concentrations (1–5 vol.%) relative to
important deposits worldwide, but much of the CGB
remain unexplored. The method outlined in this study
could greatly facilitate exploration of the vast CGB flows
located in a 500 × 250 km area of south-central BC.
Drone-based visible-light imaging may also be useful
for the exploration of lapis lazuli and pegmatite-hosted
gem deposits.
Adamo, I., Bocchio, R., Pavese, A. & Prosperi, L. 2009.
Characterization of peridot from Sardinia, Italy. Gems
& Gemology, 45(2), 130–133,
Belley, P.M. & Groat, L.A. 2020. Metamorphosed carbonate
platforms and controls on the genesis of sapphire,
gem spinel, and lapis lazuli: Insight from the Lake
Harbour Group, Nunavut, Canada and implications
for gem exploration. Ore Geology Reviews, 116,
article 103259 (10 pp.),
Bevier, M.L. 1983. Implications of chemical and isotopic
composition for petrogenesis of Chilcotin Group
basalts, British Columbia. Journal of Petrology, 24(2),
Brearley, M., Scarfe, C.M. & Fujii, T. 1984. The petrology
of ultramafic xenoliths from Summit Lake, near Prince
George, British Columbia. Contributions to Mineralogy
and Petrology, 88(1–2), 53–63,
Figure 11: South-central British Columbia,
Canada, has produced small amounts of
gem-quality peridot with good colour
but typically in small sizes. Shown here
is a rough piece (2.5 cm wide) from
Lightning Peak and three faceted stones
(1.1–1.25 ct) from the northernmost
peridot-producing locality in Figure 6.
Further gem exploration of basaltic
terranes in this region using the remote-
sensing techniques described in this
article could result in additional
production of gem-quality peridot.
Photo by Michael Bainbridge.
The Authors
Dr Philippe Maxime Belley, Pattie Shang and
Donald John Lake
University of British Columbia, Vancouver, British
Columbia, Canada
The authors thank Brad Wilson for granting access
to his mineral claim on Lightning Peak. We are
grateful to Xiaoyuan Chen for help with translating
a Chinese-language reference. We thank three
anonymous reviewers for helpful comments that
improved the manuscript.
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... Validating methodology in rocky slopes with different discontinuity characteristics [138][139][140][141][142][143][144][145] accumulation, fluvial forms, earthquakes) approach with consistent measurement and calculation processes. The methodology for Rockfall Susceptibility Assessment for 3D slope models in the form of point clouds can be used to refine the identification of potential rockfall source areas. ...
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UAS (Unmanned Aircraft Systems) technologies, also known as UAV (Unmanned Aerial Vehicle), drones, or Remotely Piloted Aircraft System (RPAS) and GIS (Geographic Information System) are recognised for the value of the results that can be achieved by their combined use. However , their use and the results achieved are rarely framed within the context of Digital Era Govern-ance (DEG), an undertaking that would significantly reduce the capabilities of knowledge transfer from the academic and/or private environment to the public domain. The purpose of this study was to highlight, by a bibliometric analysis, the areas of proposed use of this team of tools and the extent to which these can enter the sphere of interest of public administrations, especially local ones. From a methodological point of view, based on the 439 articles filtered from the Web of Science database where UAS/UAV and GIS technologies were used, several bibliometric analyses have emerged. VOSviewer and R (Bibliometrix tool) were used to conduct the bibliometric analyses. Most scientific publications that used UAV technology as a working tool have predominant applicability in pho-togrammetry, while GIS applications are found in publications dedicated to image processing, landslides , and cultural and archaeological heritage. We point out that from the point of view of international cooperation, at the level of institutions or countries, certain international organisations from the USA, China, and the central and northern European states have a high interest in this topic, and a low cooperation between academia and public administration is exhibited. The conclusion is represented by the apparent lack of framing of the results of UAS-GIS technologies usage into wider and more topical contexts, such as digital era governance, and also a reduced applicability of the research results.
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The technical evolution of unmanned aerial systems (UAS) for mineral exploration advances rapidly. Recent sensor developments and improved UAS performance open new fields for research and applications in geological and geophysical exploration among others. In this study, we introduce an integrated acquisition and processing strategy for droneborne multisensor surveys combining optical remote sensing and magnetic data. We deploy both fixedwing and multicopter UAS to characterize an outcrop of the Otanmäki FeTiV deposit in central Finland. The lithology consists mainly of gabbro intrusions hosting ore bodies of magnetiteilmenite. Large areas of the outcrop are covered by lichen and low vegetation. We use two droneborne multi and hyperspectral cameras operating in the visible to nearinfrared parts of the electromagnetic spectrum to identify dominant geological features and the extents of ore bodies via ironindicating proxy minerals. We apply band ratios and unsupervised and supervised image classifications on the spectral data, from which we can map surficial ironbearing zones. We use two setups with threeaxis fluxgate magnetometers deployed both by a fixedwing and a multicopter UAS to measure the magnetic field at various flight altitudes (15 m, 40 m, 65 m). The total magnetic intensity (TMI) computed from the individual components is used for further interpretation of ore distribution. We compare to traditional magnetic groundbased survey data to evaluate the UASbased results. The measured anomalies and spectral data are validated and assigned to the outcropping geology and ore mineralization by performing surface spectroscopy, portable Xray fluorescence (pXRF), magnetic susceptibility, and traditional geologic mapping. Locations of mineral zones and magnetic anomalies correlate with the established geologic map. The integrated survey strategy allowed a straightforward mapping of ore occurrences. We highlight the efficiency, spatial resolution, and reliability of UAS surveys. Acquisition time of magnetic UAS surveying surpassed ground surveying by a factor of 20 with a comparable resolution. The proposed workflow possibly facilitates surveying, particularly in areas with complicated terrain and of limited accessibility, but highlights the remaining challenges in UAS mapping.
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Mapping lithology and geological structures accurately remains a challenge in difficult terrain or in active mining areas. We demonstrate that the integration of terrestrial and drone-borne multi-sensor remote sensing techniques significantly improves the reliability, safety, and efficiency of geological activities during exploration and mining monitoring. We describe an integrated workflow to produce a geometrically and spectrally accurate combination of a Structure-from-Motion Multi-View Stereo point cloud and hyperspectral data cubes in the visible to near-infrared (VNIR) and short-wave infrared (SWIR), as well as long-wave infrared (LWIR) ranges acquired by terrestrial and drone-borne imaging sensors. Vertical outcrops in a quarry in the Freiberg mining district, Saxony (Germany), featuring sulfide-rich hydrothermal zones in a granitoid host, are used to showcase the versatility of our approach. The image data are processed using spectroscopic and machine learning algorithms to generate meaningful 2.5D (i.e., surface) maps that are available to geologists on the ground just shortly after data acquisition. We validate the remote sensing data with thin section analysis and laboratory X-ray diffraction, as well as point spectroscopic data. The combination of ground- and drone-based photogrammetric and hyperspectral VNIR, SWIR, and LWIR imaging allows for safer and more efficient ground surveys, as well as a better, statistically sound sampling strategy for further structural, geochemical, and petrological investigations.
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Vietnam is an important source of peridot for the international gem market. Gemological and geochemical characteristics of Vietnamese peridot from the Central Highlands are similar to those noted for other localities originating from xenoliths in alkaline basalts. This peridot was derived from a spinel lherzolite source and appeared to form at temperatures between 910° and 980°C and an assumed pressure of 2.0 ± 0.5 GPa, corresponding to a depth of around 60 km.
Baffin Island's Lake Harbour Group (LHG), a Paleoproterozoic granulite facies metasedimentary sequence rich in carbonates, contains occurrences of the gemstones sapphire (corundum), spinel (including vivid blue, cobalt-enriched spinel), and lapis lazuli (haüyne-bearing rock). Most occurrences of these gem minerals are uniquely metasedimentary (carbonates and calc-silicate rock), while a few spinel occurrences formed from metasomatic reactions between Si-Al-rich rock (syenogranite or gneiss) and marble. The metasedimentary corundum, spinel, and haüyne occurrences have similar protoliths: primarily dolomitic marls with a high Al/Si relative abundance (interpreted as sandy mud to clay siliciclastic fraction in the protolith). Kimmirut-type sapphire deposits formed via a multi-step metamorphic process under three different and specific P-T conditions. Lapis lazuli formation required the presence of evaporites to provide Na and possibly S for the blue mineral haüyne. In addition to high Al/Si calc-silicate rocks, spinel also occurs in impure dolomitic marbles with very low K/Al. Potential for Kimmirut-type sapphire deposits is expected to be restricted to metacarbonate sequences proximal to the thrust fault separating the LHG from the Narsajuaq Arc, where retrograde upper amphibolite facies mineralization is most pervasive. Spinel and Kimmirut-type sapphire deposits are expected to be found in dolomitic marble sequences rich in calc-silicate layers. The potential occurrence of lapis lazuli is more difficult to predict but deposits could be identified thanks to large geographical footprints and their color. Similar gem occurrences or deposits to those in the LHG may be found in other metacarbonate-bearing terranes with similar metamorphic conditions (and for Kimmirut-type sapphire, a similar metamorphic history). Aerial hyperspectral and photographic surveys are well-suited to gemstone exploration on southern Baffin Island thanks to excellent rock exposure with minimal sediment or plant/lichen cover. Spectral mapping of dolomite-, diopside-, phlogopite-, and scapolite-rich domains in LHG metacarbonate sequences using airborne hyperspectral data is expected to provide exploration targets. Remote sensing exploration could be used in other metacarbonate-bearing, upper amphibolite to granulite facies metamorphic terranes found in polar climates, arid climates, or at high elevation in mountainous regions where such rocks are well exposed with minimal vegetative cover.