Selenite and Satin Spar

Selenite is a transparent, crystallized form of gypsum that's created when calcium-rich salt water evaporates. It's often white with a pearlescent luster, but can also be gray, yellow, brown, reddish-brown, or green.

Satin spar is a distinct, fibrous variety of the mineral gypsum. It is widely recognized for its milky or pearly appearance and a characteristic silky, shimmering luster that looks like a ribbon of satin.

These two minerals are chemically similar and often confused for the other.