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Item # GY017004
Gypsum Selenite from
Gypsum Selenite Crystals on matrix
Intriguing  acicular crystalline inter-growth matrices  of selenite. This
very special specimen comes to us from an old collection in
Needles, CA (from the collection of Frank and Maggie  McShan).
This specimen
weighs 4oz (115 g) and measures 2.1 x 1.9 x 1.3
in (5.3 x 4.8 x 3.3 cm).
Gypsum selenite is used in making
Sheetrock (Drywall board)
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Gypsum is one of the most common, rock-forming minerals, developing thick beds formed by the
evaporation of extremely salt laden waters. Gypsum is associated with halite and sulfur. It is
deposited from lakes, seawater, hot springs, volcanic moisture, and sulfate solutions in underground
veins. Anhydrite in underground veins can be converted into gypsum by hydration from groundwater
close to surface areas. Gypsum dissolves over time in water, and is rarely found in the form of sand. A
well known oddity is the White Sands National Monument in the state of New Mexico. The unique
conditions there have produced a 275 square mile area of white gypsum sand. In 1933 President
Herbert Hoover declared the gypsum dunes a protected national monument to prevent
commercialization of the area.

When heated under appropriate conditions, gypsum forms plaster of Paris. Gypsum is extremely
useful for many practical applications and for works of art. In particular, it is used for wallboard for
buildings, as a component of concrete for the construction of highways and bridges, and as a soil
conditioner for agriculture. The Clear variety is called selenite. The translucent variety, called
alabaster, is a valuable ornamental stone. When converted to plaster of Paris, it is used in sculpture,
architecture, fire protection, and theatrical sets. There are many formations of Gypsum that make
outstanding collection specimens, and it is a favorite of rockhounds!

For a description from Wikipedia, the free encyclopedia
Stunning Colorless Selenite Crystals on Matrix
Selenite Crystals on matrix from Weeks, Nevada. Weeks is an old collecting
site between Reno and Carson City east towards Silver Springs. The photos
show this specimen in its natural state. Beautiful crystal formations on a
matrix with a green coloring. This is Old Stock Material found years ago. This
came from a collection from the 1930's through the 1950's

This Selenite weighs 4.76 oz (135g)  and measures
roughly 2.3 x 1.7 x 1.1" (59.7 x 43.6 x 29.6mm)
Item # SEL0911999A
Gypsum Selenite with Matrix from Nevada          $22.00