Geology Reference
In-Depth Information
Chlorite
(Mg,Al,Fe)
6
(Si,Al)
8
O
20
(OH)
4
Mid-green to dark
greenish-yellow
One good
cleavage gives
thin sheets
Dull to
pearly and
'micaceous'
Usually aggregates of fine
crystals, sometimes thin
tabular flakes replacing
mafic minerals in igneous
rocks
2-3
Pyrite
FeS
2
Brassy yellow,
occasionally brown or
black
Poor
Metallic;
iridescent
tarnish
Often good cubic crystal
faces, occasionally striated.
Granular aggregates,
particularly along veins in
igneous rocks
6-6.5
Zircon
ZrSiO
4
Colourless pale brown
Two poor
Adamantine/
glassy
Small prisms with terminal
faces often euhedral
7.5
