GYPSUM Flashcards
Hydrous calcium sulphate containing 20% water
Gypsum
Most common sulfate mineral and commonly found in layered sedimentary deposits in association with other evaporite minerals.
Gypsum
4 known varieties
Selenite, Satin Spar, Alabaster, Gypsite
20 million tons of crude gypsum
United States
Each producing an estimated 16 million tons.
China and Iran
Are the world’s leading gypsum producers.
China, Iran, Spain, and the United States
Large gypsum deposits occur in…
Great Lakes region
Midcontinent region
Western States
Local - Major deposits of gypsum are located in…
Batangas
Camarines Sur
Albay
Negros Oriental
Usage
Manufacture of Wallboard
Cement
Plaster of Paris
Fertilizer and soil conditioning
Hardening retarder in portland cement
- A quick-setting gypsum plaster consisting of a fine white powder (calcium sulfate hemihydrate)
- Used for recast and hold parts of ornamental plasterwork placed on ceilings and cornices.
- Plaster Casts for broken bones
Plaster of Paris
Is used for ornaments and jewelry
Satin Spar
Is carved and polished for statuary and ornamental use when pure and translucent.
Alabaster
Gypsum is a naturally occurring mineral found in layers of _____ all over the world. It is formed by the _____ of waters containing calcium and sulfates
Sedimentary rocks, evaporation and replenishment
A soft, light-colored sedimentary rock deposited in ancient seas that
covered Ohio during the Silurian Period. It occurs in both mineral form
(selenite) and as a rock in bedded layers. Gypsum occurs interbedded with
salt (halite, NaCl) and anhydrite (CaSO4).
Rock Gypsum
Transparent and some of the largest crystals found on Earth. It has been
named the transparent variety that occurs in crystals or crystalline masses.
The name derives from Middle English selenite from Latin selenites,
ultimately from Greek selēnítēs líthos (σεληνίτης λίθος, lit. ‘moon stone’).
Selinite
is a fibrous form of Gypsum. It is generally white, silky and translucent
with pearly or milky appearance although you can also find
peach/orange commonly sold as well. The name Satin Spar was first
used for a variety of Calcite (Satin Spar Calcite).
Satin Spar
A fine-grained white or lightly-tinted variety of gypsum, used
ornamentally. A variety of calcite, translucent and sometimes
banded.
Alabaster
Soft. Earthy, and impure form of Gypsum
Gypsite
Type I
Impression plaster
Type II
Dental plaster
Type III
Dental Stone
- Hydrocal, Alpha Hemihydrate
Type IV
Dental Stone (High Strength)
- Die Stone, Densite, Modified alpha hemihydrate
Type V
Dental Stone ( High Strength, High Expansion)
Mining Method of Gypsum
Surface mining
Production Process Gypsum
Excavation
Crushing
Screening
Grinding
Heating
