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World map showing blue quartz occurrences. The black dots represent magmatic/metamorphic blue quartz, blue dots represent hydrothermal blue quartz associated with Au and U deposits and the red contours represent shield units. Notice the relationship between blue quartz occurrences, shield units and orogenic belts. Modified after https://mapswire.com/world/physical-maps/.
Source publication
Abstract. Blue quartz occurs in a variety of geological settings worldwide and its colour is often produced through the Rayleigh
scattering of light off nanometre size mineral inclusions with uncertain identity. Despite this fact, dedicated mineralogical studies on
the topic are few and most references mention only the location and inferred causes...
Contexts in source publication
Context 1
... between the blue colour and host rock composition. However, it is reasonable to assume a combination of fluid and mineral inclusions capable of scattering light. Future studies on hydrothermal blue quartz from Rio delle Ossa, Italy, available to the authors, may shed some light on this potentially economically significant quartz variety (Fig. 1). ...
Context 2
... consulting a significant volume of papers reporting blue quartz, a number of 245 occurrences have been located, which outline a pattern consistent with the large-scale geological features of each respective continent. Figure 1 presents the distribution of the blue quartz occurrences identified up to this point. It is worth noting that most occurrences outline orogenic belts linked to supercontinent building events from various geological periods or border shield units. ...
Context 3
... between the blue colour and host rock composition. However, it is reasonable to assume a combination of fluid and mineral inclusions capable of scattering light. Future studies on hydrothermal blue quartz from Rio delle Ossa, Italy, available to the authors, may shed some light on this potentially economically significant quartz variety (Fig. 1). ...
Context 4
... consulting a significant volume of papers reporting blue quartz, a number of 245 occurrences have been located, which outline a pattern consistent with the large-scale geological features of each respective continent. Figure 1 presents the distribution of the blue quartz occurrences identified up to this point. It is worth noting that most occurrences outline orogenic belts linked to supercontinent building events from various geological periods or border shield units. ...
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Citations
... The scarce literature on rock forming blue quartz attributes the color to the scattering of light by submicron/nanometric inclusions, usually ilmenite or rutile, but also biotite, magnetite, graphite, and others. The consensus is that blue quartz is usually hosted by plutonic and volcanic intermediary to acidic rocks (or their metamorphic equivalent) and that, when hosted by metamorphic rocks, the occurrences are related to amphibolite-granulite facies conditions, as summed up by Pantia & Filiuță (2019). The geological significance of these occurrences is largely undetermined (Zolensky et al., 1988;Seifert et al., 2011), although potential applications of metamorphic blue quartz in determining the metamorphic history of the area of occurrence have been suggested (Pantia & Filiuță, 2021). ...
... 2040 -2060 Ma (Neves et al., 2020) Sucuru granite associated with subduction-collisional events linked to the assembly of the Nuna/Columbia supercontinent, or 2 -within-plate magmatism, as is the case with the 1871 ± 5 Ma (Costi et al., 2009) Abonari granite of the Mapuera Intrusive Suite, Amazon Craton, or the 2006 ± 24 Ma (Sparrenberger & Tassinari, 1999) Riacho dos Cavalos pegmatite of the Granite-Gneiss Complex (Goiás Tin Province). Similar connections between blue quartz occurrences and regional features have been reported by Pantia & Filiuță (2019). showing the general location of rock forming blue quartz occurrences in Brazil: 1 -Abonari; 2 -Cristalino; 3 -Porangatu; 4 -Campinorte; 5 -Serra da Mesa; 6 -Sucuri; 7 -Soledade; 8 -Pedra Branca; 9 -Riacho dos Cavalos; 10 -Mangabeira; 11 -Guanambi Batholith; 12 -Central Espinhaço; 13 -Rio dos Remédios; 14 -São Timóteo; 15 -Couro de Onça; 16 -Lagoa do Gato; 17 -Sucuru; 18 -Santa Catarina Granulite Complex; 19 -Zimbros (Modified after Paquette et al., 2015 andQueiroz &Klein, 2018). ...
Rock forming blue quartz occurrences are reported on all continents, but little is known about the specific causes for the coloration, and even less about its geological significance. The present study investigates the occurrence hosted by the metarhyolites of the Rio dos Remédios Group in order to determine the potential causes of the blue coloration and gain insight into the geological significance of the occurrence in the wider context of Brazilian geology. The optical observations have shown that the blue color is likely the result of the Rayleigh scattering of light. The color is stable even at temperatures of 800°C. The FT-IR investigations have not detected the presence of inclusions capable of scattering light. The scanning electron microscopy has shown that there are significant amounts of Fe and Ti in the system, clearly concentrated as Ti/ Fe oxides hosted by the matrix, and potentially as light scattering nanometric inclusions. This type of inclusions would likely be syngenetic with the host quartz. The alternation between the blue and colorless areas could be the result of chemical fluctuations in the melt, which may have resulted in disruptions of the crystallization of the light scattering inclusions.
... Therefore, any inclusion could scatter light, provided it has nanometric dimensions. The geologic literature on the subject most often identifies Ti bearing minerals, mostly rutile and ilmenite as the scattering particles, although tourmaline, magnetite, micas, apatite, and others have also been reported (Pantia & Filiuță, 2019), but molecular colloids enabled by structural defects caused by temperature and/or radiation, as in the case of Blue-John-type fluorite (Bill & Calas, 1978) could also be taken into account as potential light scattering particles in the case of blue quartz. ...
... Blue quartz proper is mostly associated with amphibolite and granulite facies conditions, and the occurrence pattern plots within continental scale tectonic features where such conditions were present (Pantia & Filiuță, 2019). ...
... However, it progressively loses its color when heated. Pantia & Filiuță (2019) have reported this anomalous behavior of the Albești blue quartz, without commenting of the causes or providing specific data regarding manifestation of Rayleigh scattering or heat sensitivity. The Albești occurrence is not alone in this respect, since loss of color has also been reported in the case of the blue quartz from the charnockites of Mysore, India (Jayaraman, 1939), Ollo de Sapo gneiss, Spain (Montero et al. 2009), and observed in the Pietrosu Bistriței porphyroid gneiss, Milbank granite and Cosăuți granite. ...
The blue quartz of the Albești metagranite is an interesting and puzzling occurrence in the Romanian geological landscape, both in terms of rarity and available data. The body of literature on blue quartz attributes the color to the Rayleigh/Tyndall scattering of light by nanometer/submicron inclusions, commonly identified as ilmenite or rutile, and as a theoretical possibility, fluid inclusions. The Albești blue quartz undergoes a visible loss of color at temperatures as low as 300°C, and for this reason the most commonly cited light scattering inclusions cannot be the cause of the coloration. Furthermore, there are only a handful of occurrences known to exhibit such a thermal behavior, potentially placing the Romanian occurrence in a rather exclusive class of rock forming blue quartz. The data gathered by optical observations, heat treatment, powder diffraction, infrared spectroscopy, and scanning electron microscopy have shown that the blue color is produced by light scattering, the scattering particles are sensitive to heat, recrystallization can also affect the color, and that the color is likely metamorphic in origin. Despite the fact that the identity of the scattering particles is still unknown (although fluid inclusions, and molecular colloids are suggested as potential light scattering elements), there is strong indication that the color is metamorphic in origin and that it could be used as a marker for a specific set of metamorphic conditions. The results of the present study constitute a first significant step in the understanding of the Albești blue quartz and point in the direction of future research.
