Calcite
Rio Grande do Sul, Brazil

The calcite "flower" specimen shown here measures 9cm x 11cm x 13cm, and was crystallized within a gas pocket trapped by lava flows in the state of Rio Grande do Sul, Brazil. It was acquired for the collection from Hawthorneden in 1995.


Calcite      CaCO3

Carbonate; calcium carbonate

Color and Luster: White, colorless, pale shades of gray, yellow, red, green, blue, brown to black when impure; vitreous, dull; streak white

Hardness: 3

Cleavage: Perfect in 3 directions, forming a rhombohedron

Fracture: Conchoidal, seldom observed

Crystals: Hexagonal; crystals commonly showing a rhombohedron, scalenohedron, and prism; also tabular, acicular, cleavable, granular, compact, stalactitic, oolitic, earthy; twinned crystals very common

     Calcite is the most common and widely occurring species of the carbonate mineral class. It belongs to the hexagonal - rhombohedral crystal system, and has been found in more than 700 different crystal forms(habits).

Photo by Mary Sutherland


Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals