Aragonite

Aragonite is a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate, CaCO3. The other polymorph is the mineral calcite. Aragonite’s crystal lattice differs from that of calcite, resulting in a different crystal shape, an orthorhombic system with acicular crystals. Repeated twinning results in pseudo-hexagonal forms.

Type

Mineral

Mineral Classification

Carbonate

Chemical Formula

CaCO3

Streak

White

Mohs Hardness

3.5-4

Crystal System

Orthorhombic

Color

White, red, yellow, orange, green, purple, grey, blue and brown

Luster

Vitreous, resinous on fracture surfaces

Fracture

Subconchoidal

Description

Aragonite is a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate, CaCO3. The other polymorph is the mineral calcite. Aragonite’s crystal lattice differs from that of calcite, resulting in a different crystal shape, an orthorhombic system with acicular crystals. Repeated twinning results in pseudo-hexagonal forms.