Rating
Name	Calcite (thin section)
Type	Mineral
Cleavage	Perfect rhombohedral cleavage
Colour and Pleochroism	Colorless in thin section
Relief	Moderate negative to high positive relief; Relief changes upon rotation of stage.
Form	Generally occurs as anhedral grains and aggregates, also as rhombohedral crystals
Optical Orientation	Inclined or symmetrical extinction
Twinning	Lamellar twinning common
Birefringence, δ	δ = 0.172; Due to extreme birefringence, interference colors are high order pastel pink, green and creamy white
Optical Character	Uniaxial (-)
2V	n/a
Key Characteristics	Relief which changes upon rotation of stage, extreme birefringence, rhombohedral cleavage and lamellar twinning are all diagnostic
Photograph Comments	pic 1(left): plane polarized light, magnification 40x, grains display rhombohedral cleavage and lamellae; pic 2(right): cross polarized light, magnification 40x, note lamellar twinning and creamy coloration due to extreme birefringence
Hand Sample URL	http://digicon.athabascau.ca/u?/RM,91
Subject	Minerals; Rocks; Identification photographs; Geology;
Date	2009
Format	image/jpeg
Identifier	2009-rm-0004
Collection Title	Rock and Mineral Samples
Repository	AU Digital Library
Rights	Subject to the Copyright Act

Calcite (thin section)

Description