Characteristics of Cordierite (Iolite) of Bandarguha-Orabahala Area, Kalahandi District, Odisha, India

Sk, Das; Jk, Mohanty

doi:10.4172/2381-8719.1000294

Cited by 2 publications

(7 citation statements)

References 3 publications

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“…Hematite occurs in the "bloodshot" iolite variety (India and Sri Lanka; Kammerling and Koivula, 1991;Muyal and Mattlin, 2019) as oriented crystals causing asterism (Bui et al, 2022) or as small isolated inclusions (Thor-Odin dome; present study). Iron-rich phlogopite (biotite) inclusions are reported from Wyoming (Hausel, 2003), India (Das and Mohanty, 2017), and Thor-Odin (present study). Rutile is reported in iolite from Madagascar (Graziani and Guidi, 2018) and India (Das and Mohanty, 2017) but was not observed in Thor-Odin samples.…”

Section: Inclusionssupporting

confidence: 60%

“…Iron-rich phlogopite (biotite) inclusions are reported from Wyoming (Hausel, 2003), India (Das and Mohanty, 2017), and Thor-Odin (present study). Rutile is reported in iolite from Madagascar (Graziani and Guidi, 2018) and India (Das and Mohanty, 2017) but was not observed in Thor-Odin samples. Quartz was observed as inclusions in iolite from India (Das and Mohanty, 2017); at the Thor-Odin dome, quartz was found as large inclusions on the edge of large fractured crystals but was absent in rough and faceted stones.…”

Section: Inclusionssupporting

confidence: 60%

“…Cordierite-bearing rocks in the Thor-Odin dome, like those in most other localities, are associated with rock-forming amounts of orthoamphibole (gedrite, though some localities contain anthophyllite). These rocks differ from those reported in the Bandarguha and Oraba-hala areas of India, which are principally composed of cordierite and biotite (Das and Mohanty, 2017). Iolite localities that have been subject to more extensive petrological and geochemical research, such as Thor-Odin (Hinchey and Carr, 2007) and the Geco mine (Pan and Fleet, 1995) consist of alkali-and calcium-depleted, magnesium-and aluminum-enriched metamorphic rocks with hydrothermally altered mafic volcanic (i.e., basaltic) protoliths.…”

Section: Discussionmentioning

confidence: 75%

“…Rutile is reported in iolite from Madagascar (Graziani and Guidi, 2018) and India (Das and Mohanty, 2017) but was not observed in Thor-Odin samples. Quartz was observed as inclusions in iolite from India (Das and Mohanty, 2017); at the Thor-Odin dome, quartz was found as large inclusions on the edge of large fractured crystals but was absent in rough and faceted stones. Zircon inclusions were noted from both India (Das and Mohanty, 2017) and Thor-Odin.…”

Section: Inclusionsmentioning

confidence: 87%

“…Quartz was observed as inclusions in iolite from India (Das and Mohanty, 2017); at the Thor-Odin dome, quartz was found as large inclusions on the edge of large fractured crystals but was absent in rough and faceted stones. Zircon inclusions were noted from both India (Das and Mohanty, 2017) and Thor-Odin. In the present study, zircon generally occurred in small groupings of numerous crystals associated with iron-rich phlogopite inclusions.…”

Section: Inclusionsmentioning

confidence: 99%

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Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Belley

2023

G&G

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Two gem-quality cordierite (iolite) localities, the Blue Arrow and Blue Bear occurrences, were recently discovered (in 2016 and 2021, respectively) in the mountainous Thor-Odin dome, southwest of Revelstoke in British Columbia, Canada (figure 1). They have so far produced small quantities of faceted stones (generally <2 ct, though the author has seen faceted windowed stones up to 4.76 ct from Blue Bear) and attractive cat's-eye cabochons (up to 12.02 ct, Blue Bear only). The present study seeks to gain new insights into: (1) the geological origin of the occurrences in a regional context and how they compare to the geology of other iolite deposits, (2) the nature of iolite mineralization at the Blue Arrow and Blue Bear localities, (3) the chemical composition and inclusions of Thor-Odin dome iolite, and (4) the nature of the inclusions responsible for chatoyancy. GEOLOGY OF IOLITE DEPOSITSDeposits of iolite (gem-quality cordierite) occur in magnesium-and aluminum-rich metamorphic rocks formed at amphibolite to granulite facies conditions. Many iolite occurrences are found around the world, but relatively few have been comprehensively characterized from a geological (i.e., petrological, geochemical, and geochronological) perspective.Significant deposits occur in the Bandarguha and Orabahala areas of Kalahandi District, India, where gem cordierite (with X Mg = [Mg]/[Mg + Fe] = 0.82-0.88) is hosted in granulite facies cordierite-biotite schists and gneisses, which can contain the following accessory minerals: quartz, potassium feldspar, plagioclase, sillimanite, corundum, and orthopyroxene (Das and Mohanty, 2017).

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Section: Inclusionssupporting

confidence: 60%

Section: Inclusionssupporting

confidence: 60%

Section: Discussionmentioning

confidence: 75%

Section: Inclusionsmentioning

confidence: 87%

Section: Inclusionsmentioning

confidence: 99%

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Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Belley

2023

G&G

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Feasibility Study on Color Grading of Blue Iolite Based on GemDialogue Color Comparison Charts

Liu

Guo

2023

Applied Sciences

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To explore the feasibility of applying the GemDialogue color comparison charts to the color grading of blue iolite, the color of the charts was quantified by the integrating sphere handheld spectroscopy in this paper, and the screened data were classified into a total of 9 categories using the elbow rule and K-Means clustering analysis. Using Fisher’s discriminant to perform discriminant analysis on the 9 categories that have been classified, the discriminant function equation was established separately to verify the accuracy of this classification. Finally, the color parameters of iolite samples were substituted into the discriminant formula to obtain the color grade. By combining the classification results and visual observation, it is clear that applying the GemDialogue color charts to blue iolite color grading is feasible.

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Characteristics of Cordierite (Iolite) of Bandarguha-Orabahala Area, Kalahandi District, Odisha, India

Cited by 2 publications

References 3 publications

Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Iolite from the Thor-Odin Dome, British Columbia, Canada: Geology, Chemical Composition, Inclusions, and Cause of Chatoyancy

Feasibility Study on Color Grading of Blue Iolite Based on GemDialogue Color Comparison Charts

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