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Id 54
Identification Type Mineral
Name Plagioclase
Distinguishing Features lamellar-twinning
low-birefringence
Description Plagioclase is a term for feldspars in the Na-Ca solid solution series. Without twinning patterns, there is no way to tell a difference between Na-Ca feldspars and K-feldspars (microcline and orthoclase).
Tags silicate
External Resources Plagioclase on MinDat
Imposters
Images
Unique Identification: Plagioclase
Site name: Joseph Lake
Light type: Cross-Polarized Light
Magnification: 400
Submitted by: Val Stanley
Notes: exsolution lamellae
Image Tags: none
Unique Identification: Plagioclase
Site name: Joseph Lake
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Val Stanley
Notes: none
Image Tags: none
Unique Identification: Plagioclase
Site name: Chungara
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned low relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Chungara
Light type: Cross-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned low relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Yellowstone
Light type: Cross-Polarized Light
Magnification: 630
Submitted by: Val Stanley
Notes: Twinning lamellae, with undulose extinction
Image Tags: twinned undulose-extinction
Unique Identification: Plagioclase
Site name: Yellowstone
Light type: Plane-Polarized Light
Magnification: 630
Submitted by: Val Stanley
Notes: Plagioclase with twins that persist in plane light
Image Tags: twinned
Unique Identification: Plagioclase
Site name: Yellowstone
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Val Stanley
Notes: none
Image Tags: cracked high-relief
Unique Identification: Plagioclase
Site name: Yellowstone
Light type: Cross-Polarized Light
Magnification: 400
Submitted by: Val Stanley
Notes: none
Image Tags: cracked high-relief
Unique Identification: Plagioclase
Site name: Chungara
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned medium relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Chungara
Light type: Cross-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned medium relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Chungara
Light type: Plane-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned low relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Chungara
Light type: Cross-Polarized Light
Magnification: 400
Submitted by: Blas Valero
Notes: transparent twinned low relief low birefringent
Image Tags: none
Unique Identification: Plagioclase
Site name: Reid Lake, ON
Light type: Plane-Polarized Light
Magnification: not specified
Submitted by: Andy Breckenridge
Notes: plagioclase, limestone, detrital, glaciolacustrine
Image Tags: none
Unique Identification: Plagioclase
Site name: Reid Lake, ON
Light type: Cross-Polarized Light
Magnification: not specified
Submitted by: Andy Breckenridge
Notes: plagioclase, limestone, detrital, glaciolacustrine
Image Tags: none
Unique Identification: Plagioclase
Site name: South of Java Trench, NE Indian Ocean (9 46.53 S, 102.41.95)
Light type: Cross-Polarized Light
Magnification: not specified
Submitted by: Guy Rothwell
Notes: Subhedral plagioclase crystal showing polysynthetic twinning on the albite law, twinned
Image Tags: none