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The Mineral coesite

Coesite with Ellenbergerite and Pyrope

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

Color

Colorless to white

Crystal System

Monoclinic

Properties

Streak
White
Hardness
7.5 - 8
Transparency
Transparent to translucent
Specific Gravity
3.0
Luster
Vitreous
Cleavage
None
Fracture
Conchoidal
Tenacity
Brittle

Crystal Habits

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.

Additional Information

Composition
Silicon dioxide
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

Noteworthy Localities

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.

Common Mineral Associations

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

coesite Photos



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