Yuta Yamanoi’s research while affiliated with Osaka University and other places

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Publications (12)


Micro-spectroscopic characterization of organic and hydrous components in weathered Antarctic micrometeorites
  • Article

January 2010

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43 Reads

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17 Citations

Earth Planets and Space

A. Suzuki

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Y. Yamanoi

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Eight unmelted Antarctic micrometeorite (AMMs) recovered from Kuwagata Nunatak were studied on Al-foils by infrared (IR), Raman, and visible reflection micro-spectroscopy in combination with electron microscopy. Major element abundances of the AMMs studied were found to be similar to solar abundance, although all have the common characteristic of Mg-depletion. Absorption bands around 500 nm were detected for some of the AMMs by the visible micro-spectroscopic method, and these AMMs can be assigned to Fe-hydroxide-like materials. These results suggest that the studied AMMs experienced weathering in Antarctica. Four grains showed the presence of IR H2O and CH bands similar to those of type 2 carbonaceous chondrites, while these were found to be absent in two grains, as in type 3 carbonaceous chondrites. D (disordered: 1360 cm-1) and G (graphite: 1600 cm-1) Raman band features of graphitic carbonaceous materials in these AMMs were not similar to those for type 3 but were rather close to those for type 2 and 1 carbonaceous chondrites, although some data showed a degree of deviation. The genetic classification of individual AMM grains can thus be studied by these methods, although the weathering effects and the atmospheric entry heating on organics and hydrous components need to be evaluated. These multiple micro-spectroscopic reflectance methods are useful for the characterization of precious small samples.


Fig. 1 Color values plotted in the a*-b* diagram for natural plinian pumices and the heated obsidian samples showing increasing a* and b* values for higher temperatures and for longer heating durations. Color changes for the heated obsidian are fitted by three linear trends with different gradients in the a*-b* diagram (b*/a* ratios: 23, 3.9, 2.3) for first (I), second (II), and third (III) stages. Natural plinian pumice fall deposits are from Kt-1 unit 1 (solid square with a cross) and unit 2 (bold cross) of Kuttara volcanic group, Hokkaido, Japan
Fig. 5 Relative loss of water (decrease in IR water band area around 3,600 cm −1 ) of obsidian thin sections as a function of X (=t 0.5 l −1 ; l: the sample thickness). Best fit curves {diffusion-out model from a plane sheet; Eq. 1 in the text} for experimental data at each temperature give apparent diffusivities D water
Fig. 6 Fe 2+ content changes of obsidian powders as a function of X 2 (=t 0.5 r −1 ; r: the sample radius, assumed to be 10 μm). Best fit curves {Eq. 4 in the text} of the diffusion model for experimental data at each temperature give apparent diffusivities D oxidation
Fig. 7 The best fit curves of the diffusion model {Eq. 5 in the text} for a* value (reddishness) increase in second stage of the heated obsidian as a function of X 2 (=t 0.5 r −1 ; t: the time, r: the sample radius, assumed to be 10 μm; (a). Changes with temperatures of m values in the diffusion model {Eq. 5} (b). The filled circles are m values
Fig. 8 Apparent diffusivities D as a function of temperature T (K) obtained for color change, oxidation and dehydration processes of the heated obsidian. D water was determined from the relative OH loss of obsidian thin sections (open circle; Fig. 5). D oxidation was obtained from the loss of ferrous iron (open triangle; Fig. 6), and from a* value increase (filled circle; Fig. 7a) of the obsidian powder in second stage

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Color-change processes of a Plinian pumice and experimental constraints of color-change kinetics in air of an obsidian
  • Article
  • Full-text available

March 2009

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108 Reads

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26 Citations

Bulletin of Volcanology

Colors of plinian pumices were measured by spectrocolorimetry, and their quantitative color parameters in the L*a*b* color space were determined. A series of heating experiments of obsidian was conducted to simulate the color-change processes of rhyolitic glasses. In these experiments, following three stages of color-change processes were observed. Stage I showed a rapid b* (yellowishness) increase associated with fast dehydration controlled by water diffusivity (D water). In stage II, a* (reddishness) increase was accompanied by Fe2+ decrease. Both a* increase and Fe2+ decrease can be simulated by a diffusion model. Obtained diffusivity D oxidation were about two orders of magnitude smaller than D water . The a*-value increase after the oxidation in stage III appeared to be quasi-linear with time, indicating the zeroth order reaction corresponding to the formation of hematite-like structures in rhyolitic glasses. The diffusion-limited a* increase model in stage II was applied to a natural plinian pumice fall unit to evaluate time periods of color-change processes through oxidation by air of fragmented rhyolitic materials.

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Temperature dependence of refectance spectra and color values of hematite by in situ, high-temperature visible micro-spectroscopy

January 2009

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114 Reads

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35 Citations

American Mineralogist

We measured visible reflectance spectra and colors of hematite (alpha-Fe(2)O(3)) reagent powders and a natural feldspar grain containing dispersed hematite microcrystals from room temperature LIP to 800 degrees C using an in situ, high-temperature visible micro-spectrometer with dark field optics. The spectrum of room-temperature hematite powder is characterized by a nearly constant reflectivity in the range 400-550 nm, a shoulder near 620 nm, and a reflectivity maximum near 750 nm. The reflectance spectrum is similar to the diffuse reflectance spectra Measured by a spectrophotometer and a conventional spectrometer with an integrating sphere. This result indicates that the dark field objective is Suitable for measuring visible reflectance spectra of hematite powders with the visible micro-spectrometer. The reflectance of hematite powders in the longer wavelength region (>550 nm) decreases gradually With increasing temperature. The shoulder centered around 620 nm and the reflectance maximum near 750 nm also become indistinct at high temperatures. The calculated L* (dark-light), a* (red-green). and b* (blue-yellow) color values decrease with increasing temperature. This means that the red color of hematite becomes black with temperature increase. The calculated absorption intensities (Kubelka-Munk functions) Suggest that this temperature dependence of the hematite powder-reflectance spectra can be mainly explained by a change in hand gap absorption edges for a semiconductor (Urbach rule). The visible spectra and colors of a natural feldspar grain containing dispersed hematite microcrystals show a similar change with temperature, indicating that the temperature dependence can be observed under natural conditions at high temperatures, Such as in volcanic eruptions.


Color measurements of volcanic ash deposits from three different styles of summit activity at Sakurajima volcano, Japan: Conduit processes recorded in color of volcanic ash

November 2008

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172 Reads

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44 Citations

Journal of Volcanology and Geothermal Research

Yuta Yamanoi

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[...]

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Tadashi Yokoyama

We measured quantitatively colors of volcanic ash deposits erupted from three different styles of summit activity (Strombolian activity, Vulcanian explosions and continuous ash venting activity) at Sakurajima volcano from 1974 to 1985. Colors of Strombolian ash samples have larger yellow components of their visible spectra (b⁎ values) than those of explosion and continuous venting ash samples. Colors of explosion ash samples show larger variation in both red and yellow components of their visible spectra (a⁎ and b⁎ values, respectively), while colors of continuous venting ash samples are in the narrow ranges within colors of explosion ash samples. Colors of components with lower densities than 3.1 g/cm3 (groundmass and phenocrystic plagioclase) obtained by magnetic and heavy liquid separation methods are similar to the unseparated bulk ash samples. This result suggests that the color variations of ash deposits are mainly originated from the particles composed of groundmass. The particles can be classified into three different types of particles with different vesicularity and crystallinity (vesicular particle [VP], dense particle with vesicles [DPV] and dense particle without vesicles [DP]). Analytical results of component proportions, chemical compositions of groundmass glasses, ferrous iron contents and surface ferric materials show that (1) VP has larger yellow components of the visible spectrum (b⁎ values) and high ferrous iron content, and is less crystallized than the DP and DPV, (2) DP has larger red and yellow components of its visible spectrum (a⁎ and b⁎ values, respectively) and involves ferric materials on the surfaces produced by oxidation process, and (3) DPV has smaller red and yellow components of its visible spectrum (a⁎ and b⁎ values, respectively) and involves less ferric materials on the ash surfaces. Color differences of ash deposits from three different activity styles can be explained by the different mixing ratios of VP, DPV and DP. During the Strombolian activity, the VP is a main component in the ash, which is formed from relatively less degassed and crystallized magma. In the Vulcanian explosion and continuous ash venting activity, the proportions of DPV and DP in ash are larger than that in the Strombolian activity. The highly crystallized DP may correspond to a vent cap, and DPV to a magma below the cap. The color measurements of ash deposits provide information on the pre-eruptive processes at the shallower levels of a conduit.


Table 4 . The estimated optical depth of the atmosphere with error and coefficient of determination.
Fig. 5. The reflectance image of the Moon at 950 nm and its histogram.
Fig. 6. Comparison between our re fl ectance image (a) and the Clementine UV/VIS image (c) at 950 nm around Tycho. Re fl ectance pro fi les (b) and (d) are derived from the line de fi ned by three points: (Lat: 43.3 ◦ S, Long: 20.0 ◦ W)-(Lat: 43.3 ◦ S, Long: 11.1 ◦ W)-(Lat: 43.3 ◦ S, Long: 0.0 ◦ W) on (a) and 
Estimation of the lunar reflectance by ground-based observation using a tunable liquid-crystal filter telescope

April 2008

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129 Reads

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11 Citations

Earth Planets and Space

Lunar reflectance data are useful not only for lithological identification of the lunar surface but also for radiometric calibration and determination of exposure time for optical sensors of lunar probes. To gain data on lunar reflectance, we acquired multi-band images (five bands: 650, 750, 900, 950, and 1000 nm) of the lunar surface and those of some standard stars using a liquid-crystal tunable filter (LCTF) telescope located on the peak of Mt. Haleakala (Hawaii, USA). The data obtained indicate that the reflectance data of Clementine UV/VIS is too high and that the correction factor is 0.59±0.06 at 950 nm. Our new reflectance data are available to the public at the web site of one of authors (K.S.). We report here our method of deriving the lunar reflectance images from the ground-based observation with a hyperspectral telescope for the users of our reflectance data. The results suggest that ground-based observation is more suitable for the radiometric calibration of the sensor of a lunar probe than laboratory data.


The absorption-peak map of Mare Serenitatis obtained by a hyper-spectral telescope

April 2008

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34 Reads

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1 Citation

Earth Planets and Space

The Mg-number [Mg# = atomic Mg/(Mg+Fe)] serves as an important petrologic discriminator when analyzing and understanding lunar rocks. Variations in the Mg# shift the wavelength of the absorption spectra of ferrous iron, which peak at around 1000 nm. Based on the image cubes of the Moon obtained by the Advanced Lunar Imaging Spectrometer (ALIS), we detected the shift in the absorption spectra of ferrous iron and built up an absorption-peak map of Mare Serenitatis. The wavelength of the absorption peak shows an 11-nm shift in Mare Serenitatis. Since the degree of space weathering can be considered to be almost the same as that within the same lava unit and Ca content cannot change without changing Mg# during magma differentiation, these shifts of the peak absorption spectra suggest that there is Mg# variation in at least the same lava unit.


Colors of Volcanic Ashes From 3 Different Summit Eruptions of Sakurajima Volcano, Japan

December 2006

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160 Reads

Colors of volcanic ashes from summit eruptions of Sakurajima volcano were measured quantitatively and their relationship to eruption styles was investigated. Three eruption styles (I: strombolian eruptions which precede vulcanian explosions, II: vulcanian explosions and III: continuous ash eruptions after the vulcanian explosions) were distinguished from seismic waveform data measured by Sakurajima Volcano Research Center of Kyoto university. Volcanic ash samples from these eruptions have different color trends in CIE L*a*b* color space, although they have almost the same bulk chemical compositions. The colors of volcanic ashes from strombolian eruptions (I) have higher b* (yellow) values than the others, and the colors of ashes from vulcanian explosions (II) have larger dispersion in a* (red) values than those of continuous eruptions (III). By using heavy liquid and magnetic mineral separations, origins of the color differences were considered to be mainly due to the groundmass (vesiculated pumice-like grains + lithic fragments). The point counting under SEM of the groundmass revealed the abundance of pumice-like grains in the ash I. On the other hand, the lithic fragments are generally rich in the ashes II and III. Therefore, the high b* values of ash I can be originated from the pumice-like grains. The colors of groundmasses of ashes II and III after mineral separation have varying a* values with low b* values almost the same as the natural ashes before the separation. The selective dissolution of iron from the natural ashes resulted in the significant decrease of a* values approaching to the similar a* and b* values. The ferrous contents in their groundmasses determined by wet chemical analyses decreased with increasing a* values. Therefore, the a* variation can be attributed to the iron oxidation at the surface of the groundmass. In fact, the color variation trend of ashes II and III is similar to that of rhyolitic glass powders oxidized by heating in air. By comparing with the reported geophysical model, the ash I might be generated from vesiculated magma that erupted rapidly, while the ashes II and III experienced oxidation process in the volcanic vent covered possibly by a cap rock.


Fig. 2. Excess pressure generated by groundmass crystallization in a shallow magma pocket. Bold and thin lines represent the excess pressure for magmas with initial vesicularity of 65 and 0 vol%, respectively. Dotted lines indicate the excess pressures at crystal content of 56 vol%
Fig. 3. Variation of excess pressure in a conduit flow of lava dome extrusion (Reprinted by permission from Nature, Vol. 402, 3741, 1999. Copyright: Nature Publishing Group). Curves are shown for values of the permeability coefficient k 0 from values of 0 to 100.
Fig. 4. Variation of excess pressure in a conduit, assuming that a conduit plug at 0 m depth prevents ascent of vesicular magma from magma chamber at 3 km depth. Allows with 500, 100 and 50 m indicate the variation curves assuming that a gas chamber with the vertical length of 500, 100 and 50 m, respectively, exists at the top of conduit. All the variation curves overlap up to 500 m depth. The variation curves for the vertical length of 500, 100 and 50 m bifurcates at 500, 100 and 50 m depth, respectively.
Pressurization processes of magmas in a shallow conduit to cause vulcanian eruption

June 2006

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77 Reads

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3 Citations

Japanese Magazine of Mineralogical and Petrological Sciences

Vulcanian eruptions are relatively frequent eruptive phenomena in island arc volcanism. The high frequency provides us many opportunities to observe the eruptive behavior and to sample the erupted materials. Vulcanian activity of the Sakurajima volcano located at southern Kyushu in Japan has continued since 1955 and been precisely monitored by Sakurajima Volcano Observatory. Therefore, the vulcanian eruptions of Sakurajima volcano can be a common, interesting target to study the eruptive behavior from the various viewpoints of material analysis, geophysical observation and numerical modeling. Recently, many researchers have focused on pressurization processes of magmas in shallow conduits to cause vulcanian eruptions. In this paper, we review several studies on observations and models of generation of excess pressure in shallow conduit magmas just before vulcanian eruptions. We evaluate the possibility of pressurization processes by dehydration-induced crystallization and buoyancy of vesicular conduit magmas. The results of this study indicate that the dehydration-induced crystallization is not effective for excess pressure generation, if crystallizing magma in shallow conduit contains a significant amount of exsolved gas phase. Instead, excess pressure can be generated in a shallow conduit by buoyancy of vesicular conduit magma, when partially solidified magma at the vent of conduit prevents magma ascent and the conduit is filled with vesicular magmas from magma chamber located at ca. 3 km depth to the shallow conduit. (in Japanese with English figure and figure caption)


The time scale evaluation of volcanic eruptions by dehydration and color change rates and permeabilities of volcanic materials

January 2006

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12 Reads

In order to evaluate quantitatively time scales for volcanic eruptions, dehydration and color change rates of volcanic eruptive materials have been experimentally investigated. The dehydration rates of volcanic glasses (rhyolite to basalt) and some representative minerals such as hornblende and muscovite have been measured by in-situ infrared (IR) microspectroscopy with a heating stage. The dehydration rates of volcanic glasses have been found to be primarily controlled by diffusion of molecular water (H2O). Based on the apparent H2O diffusivity in rhyolitic glasses, rough time scales for diffusion-limited dehydration of the magma for some Plinian eruptions are estimated to be in the order of a few hundreds of seconds. This can be considered as a minimum time scale for magma ascent from the magma chamber to the fragmentation level during volcanic eruptions. A series of heating experiments of obsidian was conducted to simulate the color changes during natural oxidation processes of rhyolitic glasses. The color change rate of dry obsidian including ferrous iron might be controlled by cation diffusion, and is 2 to 4 orders of magnitude slower than the dehydration rate. This diffusion- limited oxidation model was applied to colors of some natural plinian pumices to estimate time scale ranges of plinian eruptions. The estimated travel time of magma from the fragmentation level to the lower parts of plinian eruption column ranged from 1 to 100 minutes for 2 typical plinian deposits. The details of color change processes are now being studied by in-situ high temperature visible microspectroscopy for some representative mineral phases such as olivine and the effects of oxygen fugacity on the color change rates have been evaluated. The permeabilities of volcanic materials have been measured by using a newly developed gas permeameter for small samples. The gas permeability in vesiculated volcanic materials appeared to differ for varying pore structures due possibly to the different pore connectivity. These permeability variations resulting in different degassing rates from magma may affect the time scale of volcanic eruptions. These experimentally obtained dehydration rates, color change rates and permeabilities can be used to evaluate time scale ranges of some natural volcanic eruption processes.


In Situ High-Temperature Visible Microspectroscopy for Volcanic Materials

December 2005

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9 Reads

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7 Citations

Applied Spectroscopy

In situ high-temperature visible microspectroscopy has been developed in order to study color change kinetics of volcanic materials. Olivine thin sections put on a synthetic alumina plate are heated on a heating stage at 600-800 degrees C under a visible microspectroscope. Changes in visible absorption spectra are monitored every 60 s for 5 hours. The obtained high-temperature visible spectra showed a gradual increase with time in absorbance in the shorter wavelength region (400-600 nm). The 430 nm absorbance (ligand field transition of Fe3+ increased more with time at higher temperatures. Assuming diffusional transport in plane sheets, apparent diffusion coefficients were determined at temperatures of 600-800 degrees C. The activation energy for this diffusion in olivine is 208 +/- 17 kJ/mol. This activation energy value is similar to those for the metal vacancy diffusion in olivine. This newly developed in situ high-temperature visible microspectroscopy can provide kinetic measurements of visible spectral change of materials at high temperatures such as volcanic materials.


Citations (8)


... To further determine the optical properties of the obtained iron mining waste, Solid UV diffuse reflectance analysis, a technique commonly used to determine the optical properties of solid materials in the UV and visible wavelengths range, was used. Generally, iron mining waste shows a high absorption of ultraviolet blue light as shown in Fig. 2(a) and the spectra of diffuse reflectance of iron mining waste is in good agreement with the spectrum obtained by Yamanoi et al. [60]. The diffuse reflectance spectra shown in Fig. 2 (a) indicate that the sample exhibited a band at about 750 nm due to the 6 A 1 → 4 A 2 single electron iron transition in the hematite phase, which is more prominent in this sample because of the increase in the hematite content after the thermal treatment. ...

Reference:

Sustainable Water Treatment: Harnessing Mining Waste as Catalysts for Sicomet Green Degradation
Temperature dependence of refectance spectra and color values of hematite by in situ, high-temperature visible micro-spectroscopy
  • Citing Article
  • January 2009

American Mineralogist

... The first-order carbon peaks of polyaromatic OM appear at ∼1,364 cm 1 (the D band, due to sp 3 carbon bonding and the breathing motion of sp 3 atoms in rings) and 1,592 cm 1 (the G band, due to stretching mode of sp 2 atoms in polyaromatic rings) (Ferrari & Robertson, 2000;Starkey et al., 2013;Suzuki et al., 2010;Tuinstra & Koenig, 1970). The exact values of the spectral parameters of these peaks (their positions (ω), full-widthhalf-maxima (Γ), and amplitudes (Ι)) are modified as a result of thermal metamorphism because their structures are sensitive to heating, and elevated temperatures cause them to be more graphitic and increase their aromaticity (Beyssac et al., 2002;Ferrari & Robertson, 2000;Sadezky et al., 2005;Tuinstra & Koenig, 1970). ...

Micro-spectroscopic characterization of organic and hydrous components in weathered Antarctic micrometeorites
  • Citing Article
  • January 2010

Earth Planets and Space

... The measured water content of the groundmass glass (<1.07 wt.%) was smaller than the 1.8-2.2 wt.% contained in groundmass glass of a volcanic bomb from an 30 October 1975, explosion (Takeuchi et al. 2006). The measured water contents were generally higher than those expected for glass formed at atmospheric pressure (0.13 wt.% in10 5 Pa). ...

Pressurization processes of magmas in a shallow conduit to cause vulcanian eruption

Japanese Magazine of Mineralogical and Petrological Sciences

... The Raman spectra of both the unmelted AMMs and the Moss CO3 carbonaceous chondrites were measured using a visible-Raman micro-spectrometer (Yamanoi et al., 2004). For measuring Raman spectra, the sample is excited by a 514.5-nm ...

Color change of a scoria and simulation heating experiments by spectro-colorimetry
  • Citing Article
  • September 2003

Geochmica et Cosmochimica Acta

... The color of volcanic ejecta has also been studied as an indicator of transitions in eruption styles or changes in the environment surrounding vent systems. This is because mineral phases have unique colors depending on their chemistry and molecular structure (Kennard and Howell 1941;Nassau 1978), and the processes during magma ascent toward the surface could change the mineral species and their composition through reactions with the melt under possibly changing fugacity conditions (Miyagi and Tomiya 2002;Yamanoi et al. 2008;Moriizumi et al. 2009;Miyagi et al. 2013). Despite pioneering studies, the colors of natural volcanic samples are often not described objectively, even with available standards like color charts (Geological Society of America 1964). ...

Color measurements of volcanic ash deposits from three different styles of summit activity at Sakurajima volcano, Japan: Conduit processes recorded in color of volcanic ash
  • Citing Article
  • November 2008

Journal of Volcanology and Geothermal Research

... Several ground-based observations also show differences in the results. The ROLO reflectance is on average about 13% lower than that of observations performed by Velikodsky et al. [118], while the former is in good agreement with the results of Saiki et al. [119,120]. The most typical application of the model at present remains to detect the response trend over time, although this is somewhat dependent on the observed sequence phase angle. ...

Estimation of the lunar reflectance by ground-based observation using a tunable liquid-crystal filter telescope

Earth Planets and Space

... The color of volcanic ejecta has also been studied as an indicator of transitions in eruption styles or changes in the environment surrounding vent systems. This is because mineral phases have unique colors depending on their chemistry and molecular structure (Kennard and Howell 1941;Nassau 1978), and the processes during magma ascent toward the surface could change the mineral species and their composition through reactions with the melt under possibly changing fugacity conditions (Miyagi and Tomiya 2002;Yamanoi et al. 2008;Moriizumi et al. 2009;Miyagi et al. 2013). Despite pioneering studies, the colors of natural volcanic samples are often not described objectively, even with available standards like color charts (Geological Society of America 1964). ...

Color-change processes of a Plinian pumice and experimental constraints of color-change kinetics in air of an obsidian

Bulletin of Volcanology

... We used a binocular reflectance microscope (Nikon SMZ800) with a visible light spectrometer at wavelengths of 400-700 nm ( Fig. 3) (Glacier X, BWTECK Inc., Plainsboro, NJ, USA) (Yamanoi and Nakashima 2005). As noise signals are large in the 400-450 and > 700 nm ranges due to the less controlled light path in the microscope, we used signals of 450-700 nm for the analyses in this study. ...

In Situ High-Temperature Visible Microspectroscopy for Volcanic Materials
  • Citing Article
  • December 2005

Applied Spectroscopy