Chlorite

Formula

Sheet silicate

Crystal system: monoclinic (+) (-)

Colour in hand specimen: green 
Cleavage: one, good 
Hardness: 2-3

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

L100 Alkali granite 
L101 Granite 
L120 Granodiorite 
L130 Andesite, porphyritic (porphyrite) 
L161 Basalt, amygdaloidal 
L201 Tuff 
L504 Garnet schist