Apatite on Calcite with Pyroxene
Otter Lake District
Quebec, Canada
This crystal measures 7.5cm x 1.5cm
Apatite Ca5(PO4)3(F,Cl,OH)
Phosphates; calcium fluorine-chlorine-hydroxl phosphate, often with some manganese and cerium
Color and Luster: Green, brown, red, yellow, violet, pink, white, colorless; greasy, vitreous; streak white
Hardness: 5
Cleavage: Poor, one direction crosswise
Fracture: Uneven
Crystals: Hexagonal; usually short to long prismatic; frequently tabular; also massive, coarse granular to compact stalactitic, earthy, oolitic
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
Note: Apatites from this district are generally fluorapatites
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals