Rating
Name	Dolomite (thin section)
Type	Mineral
Cleavage	Perfect rhombohedral cleavage
Colour and Pleochroism	Colorless in thin section, weathered or altered samples may appear brown or iron stained due to iron oxides
Relief	Low negative to high positive relief; Relief changes upon stage rotation
Form	Coarse to fine grained aggregates most common, also rhombohedral crystals
Optical Orientation	Symmetrical or inclined extinction
Twinning	Lamellar twinning common
Birefringence, δ	δ = 0.179 - 0.182. 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 δ, rhombohedral cleavage and lamellar twinning are all diagnostic. Dolomite usually has higher refractive indices than calcite and may be colorless or iron stained where calcite is generally colorless.
Photograph Comments	pic 1(left): plane polarized light, magnification 100x, note lozenge shape of some grains due to rhombohedral cleavage and iron stained nature of some grains; pic 2(right): cross polarized light, magnification 100x
Hand Sample URL	http://digicon.athabascau.ca/u?/RM,76
Subject	Minerals; Rocks; Identification photographs; Geology;
Date	2009
Format	image/jpeg
Identifier	2009-rm-0006
Collection Title	Rock and Mineral Samples
Repository	AU Digital Library
Rights	Subject to the Copyright Act

Dolomite (thin section)

Description