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Coesite with Ellenbergerite and Pyrope

The Mineral coesite

Coesite is a very rare mineral that forms in unique ultra high metamorphism usually as a result of meteorite impacts. It was named after American chemist Loring Coes, Jr. (1915-1978), who first synthesized Coesite in 1953 before it was naturally discovered in Barringer Crater in 1960.
Chemical Formula SiO2
Composition Silicon dioxide
Color Colorless to white
Streak White
Hardness 7.5 - 8
Crystal System Monoclinic
Crystal Forms
and Aggregates
Occurs only in microscopic prismatic and tabular crystals. It is usually as a white dust or glassy material around Quartz sand pebbles. A synthetic form has been produced with large crystals resembling those of Gypsum.
Click here for a detailed explanation on the crystal structure of Coesite and other forms of silica.
Transparency Transparent to translucent
Specific Gravity 3.0
Luster Vitreous
Cleavage None
Fracture Conchoidal
Tenacity Brittle
In Group Silicates; Tectosilicates; Silica Group
Striking Features Occurrence, hardness
Environment Found at crater sites from the impact of a meteorite, where it forms under extreme heat and pressure, and in ultra-high-pressure eclogite rocks.
Rock Type Metamorphic, Meteoric
Popularity (1-4) 4
Prevalence (1-3) 3
Demand (1-3) 3


Quartz, Tridymite, Cristobalite, Stishovite

Natural Coesite has been reported in the Barringer Crater (also known as Meteor Crater) in Coconino Co., Arizona; Sinking Springs Crater, Ohio; the Kentland Crater, Newton Co., Indiana; the Riess-kessel Crater, Bavaria, Germany; Kimberly, South Africa; and the Dora Maira Massif, Piedmont, Italy.

Iron/Iron-Nickel, Diamond, Pyrope, Quartz, Ellenbergite

coesite PHOTOS
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