Gypsum Varieties and Properties Quiz

Study Notes

Gypsum Varieties Overview

Gypsum is a sulfate mineral with the chemical composition of hydrous calcium sulfate, CaSO4·2H2O.
It crystallizes in the monoclinic system and is characterized by its perfect cleavage and low hardness.
Common colors include clear, colorless, white, gray, yellow, red, and brown.

Physical Properties of Gypsum

Mohs hardness ranges from 2.3 to 2.4, making it a defining mineral for hardness 2.
Specific gravity is around 2, with diagnostic properties including cleavage and low hardness.
Luster varies from vitreous to silky, with a white streak and transparency ranging from transparent to translucent.

Alabaster Gypsum

Alabaster is a fine-grained, massive variety of gypsum, known for its translucent appearance.
Identifiable by a crystal habit that is generally prismatic with a color range including colorless, white, yellow, brown, and gray due to impurities.
Mohs hardness is noted at 1.5-2, with perfect cleavage on {010} and a unique twinning tendency on {110}.

Satin Spar

Satin spar is characterized as a fibrous variety of gypsum, often with elongated fractures.
It can display a range of colors, including brown-green, gray-green, and gray-white, depending on impurities.
Cleavage is perfect and distinct, with a Mohs hardness of around 2 and a specific gravity of 2.9.

Selenite Gypsum

Selenite is distinguished by its transparent and colorless (or lightly colored) crystal form.
Identically composed as other gypsum varieties, with a crystal habit that appears earthy and dull.
Its notable properties include a non-radioactive and non-magnetic nature, making it unique among gypsum varieties; it also exhibits fluorescence.

Applications of Gypsum

Gypsum is primarily used in construction, especially for manufacturing drywall, plaster, and joint compounds.
It also serves as a treatment for agricultural soil.

Description

Test your knowledge on the different varieties of gypsum, including its physical properties and unique characteristics. This quiz covers aspects such as hardness, specific gravity, and notable types like alabaster. Challenge yourself to identify and understand gypsum better!