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Chlorite
Title
Chlorite
Subject
Chlorite is a common high-temperature alteration product of ferromagnesian minerals (such as biotite) in igneous rocks. It is stable in the upper part of the crust and is a major constituent of the metamorphic rocks known as greenschists.
Description
Formula
(Mg,Fe2+,Fe3+,Mn,Al)12[(Si,Al)8O20](OH)16
Structure
Sheet silicate
Crystal System
Crystal system: monoclinic (+) (-)
Physical Properties
Colour in hand specimen: green
Cleavage: one, good
Hardness: 2-3
Optical Properties
Colour in plane polarised light: colourless or green
Pleochroism: weak to moderate
Relief: low
Birefringence: anomalous (blue or brown colours that do not appear in the Michel-Levy chart)
Extinction: straight
Rock Specimens
Mineral Name
chlorite
Citation
“Chlorite,” 1A Collections, accessed April 9, 2024, https://wserv3.esc.cam.ac.uk/p1acollections/items/show/53.