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Cummingtonite

Cummingtonite

Grunerite is an end member of the cummingtonite-grunerite series. Structure and composition are anal-ogous to cummingtonite. The name grunerite is by definition restricted to compositions close to end member Fe7Si8O22(OH)2.

Grunerite

Spodumene

Spodumene

Cummingtonite

Margarite

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Jadeite

Hand Specimen identification: Association with other high-pressure minerals, form, two (rarely seen) cleavages at near 90°, green color, and tenacity identify jadeite. It is distinguished from nephrite by its luster. An optical microscope may be needed to confirm identification. Chemical Composition : NaAlSi2O6 Hardness : 61 2 to 7 Specific …

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Augite

Hand Specimen identification: Association, form, two cleavages at 86° to 87°, and color identify pyroxene, but differentiating augite is problematic without X-ray data. White to green or pale green pyroxenes are often diopside; augite tends to be dark green or black. Augite is occasion-ally confused with hornblende. Plate 6.1 is …

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Pigeonite

Hand Specimen identification: Occurrence as phenocrysts in volcanic rock, form, two cleavages at 86°, and color identify pyroxene, but telling pigeonite from the other dark-colored pyroxenes is difficult. Only X-ray studies can make the distinction. Chemical Composition : (Ca,Mg,Fe)2Si2O6 Hardness : 6 Specific Gravity3.4 Cleavage/Fracture : two perfect prismatic {110}/uneven …

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