Plagioclase Feldspar (thin section)
|
Rating |
|
|
Name |
Plagioclase Feldspar (thin section) |
|
Type |
Mineral |
|
Cleavage |
Cleavages intersect at 93 °, usually not observed in thin section |
|
Colour and Pleochroism |
Colorless in thin section; Grains may appear cloudy due to alteration |
|
Relief |
Low negative or positive relief |
|
Form |
Euhedral to anhedral grains, tabular or lathlike habit |
|
Optical Orientation |
Inclined extinction; Oscillatory zoning common; Optical orientation varies with composition and thus can be used to determine composition |
|
Twinning |
Polysynthetic twinning (albite, pericline twin laws), penetration twinning (simple twin law) |
|
Birefringence, δ |
δ = 0.007 - 0.013; Maximum interference colors first-order grey or white |
|
Optical Character |
Biaxial (+) or (-) |
|
2V |
2Vx = 45 - 102° |
|
Key Characteristics |
Low relief, colorless nature, polysynthetic twinning and oscillatory zoning are diagnostic of plagioclase |
|
Photograph Comments |
pic 1(left): plane polarized light, magnification 40x; pic 2(right): cross polarized light, magnification 40x, mineral exhibits polysynthetic twinning |
|
Hand Sample URL |
http://digicon.athabascau.ca/u?/RM,75 |
|
Subject |
Minerals; Rocks; Identification photographs; Geology; |
|
Date |
2009 |
|
Format |
image/jpeg |
|
Identifier |
2009-rm-0012 |
|
Collection Title |
Rock and Mineral Samples |
|
Repository |
AU Digital Library |
|
Rights |
Subject to the Copyright Act |
Add tags for Plagioclase Feldspar (thin section)
you wish to report:
...
