Selenite
Selenite (CaSO
4
ยท2H
2
O) is a common mineral in sedimentary
environments so I see a lot of it when looking
fossils.
Enormous crytals have been found in
a cave in Mexico
.
This mineral is often called, "Gypsum,"
and is the source of Plaster of Paris.
It is the standard for hardness 2 on the Mohs scale.
It cleaves readily and thin pieces can be bent.
Single crytals—selenite forms monoclinic crystals.
These are twinned crystals.
This crystal group is often referred to as a selenite rose.
