Show UniqueIdentification

Id 138
Identification Type Mineral
Name Pyroxene
Distinguishing Features
Description A class of aluminosilicate minerals, many of them iron and/or magnesium-bearing, having wide distribution in igneous and metamorphic rocks and occurring commonly as minor but often prominent constituents in sedimentary environments. In smear slides, Mg-Fe pyroxenes are typically shades of green or brown (depending on mineral species) in plane-polarized light, often display moderate to strong pleochroism, and show moderate birefringence in cross-polarized light. Extinction can be either parallel (minerals in the orthopyroxene class) or inclined (clinopyroxene minerals). Pyroxene minerals have relatively high specific gravity, and will tend to concentrate with other heavy mineral species in winnowed or density-sorted depositional environments.
Tags silicate
External Resources
Imposters
Images
Unique Identification: Pyroxene
Site name: Lake of the Woods
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Val Stanley
Notes: 90 degree cleavages
Image Tags: green high-relief perpendicular-cleavage
Unique Identification: Pyroxene
Site name: Lake of the Woods
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Val Stanley
Notes: 90 degree cleavages
Image Tags: high-relief perpendicular-cleavage
Unique Identification: Pyroxene
Site name: Bay Horse Lake, ID
Light type: Cross-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Large dark-colored magmatic pyroxene grain from a basaltic tephra originating in the Snake River Plain, Idaho. First-and-second-order birefringence is obscured by strong grain coloration.
Image Tags: pyroxene mafic-mineral moderate-birefringence prismatic ferromagnesian
Unique Identification: Pyroxene
Site name: Bay Horse Lake, ID
Light type: Plane-Polarized Light
Magnification: 400.0
Submitted by: Mark Shapley
Notes: Large dark-colored magmatic pyroxene grain from a basaltic tephra originating in the Snake River Plain, Idaho. Fragmentary plant matter underlies the grain.
Image Tags: pyroxene mafic-mineral moderate-birefringence prismatic ferromagnesian

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