Name/Title
GypsumEntry/Object ID
2004.1.20Description
Assemblage Zone: pegmatite dikes
Chemical Composition: CaSO4-2(H2O)
Crystal System: Monoclinic System
Description: Common Name:Gypsum
Group Name: Sulfates
Chemistry: CaSO4-2(H2O), Hydrated Calcium Sulfate
Location: Guangi Zhuang, China
Descrption: Tower of gypsum white with pink from cinnbar with clear selenite crystals coming out.
PHYSICAL CHARACTERISTICS:
Color is usually white, colorless or gray, but can also be shades of red, brown and yellow.
Luster is vitreous to pearly especially on cleavage surfaces.
Transparency crystals are transparent to translucent.
Crystal System is monoclinic; 2/m
Crystal Habits include the tabular, bladed or blocky crystals with a slanted parallelogram outline. The pinacoid faces dominate with jutting prism faces on the edges of the tabular crystals. Long thin crystals show bends and some specimens bend into spirals called "Ram's Horn Selenite" Two types of twinning are common and one produces a "spear head twin" or "swallowtail twin" while the other type produces a "fishtail twin". Also massive, crusty, granular, earthy and fiberous.
Cleavage is good in one direction and distinct in two others..
Fracture is uneven but rarely seen.
Hardness is 2 and can be scratched by a fingernail.
Specific Gravity is approximately 2.3+ (light)
Streak is white.
Associated Minerals are halite, calcite, sulfur, pyrite, borax and many others.
Other Characteristics: thin crystals are flexible but not elastic, meaning they can be bent but will not bend back on their own. Also some samples are fluorescent. Gypsum has a very low thermal conductivity (hence it's use in drywall as an insulating filler). A crystal of Gypsum will feel noticeably warmer than a like crystal of quartz.
Best Field Indicators are crystal habit, flexible crystals, cleavage and hardness.
Fracture: uneven but rarely se
Hardness: 2 Gypsum
Luster: Pearly
Occurrence: Gypsum is one of the more common minerals in sedimentary environments. It is a major rock forming mineral that produces massive beds, usually from precipitation out of highly saline waters. Since it forms easily from saline water, gypsum can have many inclusions of other minerals and even trapped bubbles of air and water.
Rock Type: Sedimentary
Specific Gravity: 2.3
Streak: Whie
Variety: Gypsum has several variety names that are widely used in the mineral trade.
"Selenite" is the colorless and transparent variety that shows a pearl like luster and has been described as having a moon like glow. The word selenite comes from the greek for Moon and means moon rock. Another variety is a compact fiberous aggregate called "satin spar" . This variety has a very satin like look that gives a play of light up and down the fiberous crystals. A fine grained massive material is called "alabaster" and is an ornamental stone used in fine carvings for centuries, even eons. Crystals of gypsum can be extremely colorless and transparent, making a strong contrast to the most common usage in drywall. The crystals can also be quite large. Gypsum is a natural insulator, feeling warm to the touch when compared to a more ordinary rock or quartz crystal. Sheets of clear crystals can be easily peeled from a a larger specimen.Collection
Suomynona Mineral CollectionAcquisition
Accession
2004.1Source or Donor
Suomynona Mineral CollectionAcquisition Method
DonationDimensions
Width
3-1/2 inDepth
5-1/2 inLength
19 inDimension Notes
Dimension taken at widest pointsLocation
Location
Wall
CenterBuilding
Freida Smith HallCategory
PermanentMoved By
Steve MillerDate
June 18, 2013Location
Container
centerDrawer
top tierShelf
south side, south sideWall
centerHallway
Discovery HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Wendy MondryDate
August 25, 2009Location
Shelf
cubby, cubbyWall
northRoom
Wood room, Delmar Smith HallBuilding
Crater Rock MuseumCategory
PermanentMoved By
Catherine BoydDate
December 26, 2008Location
Drawer
LeftShelf
BottomCabinet
Case #27Wall
Back WallRoom
Freida HallBuilding
Freida Smith HallCategory
Permanent
