Crystal Apatite

Chemical Formula

Apatite is mineral group with the following chemical formula applied to the most common members of the primary group (excluding the extended Apatite supergroup):

Ca₅(PO₄)₃(F,Cl,OH)

Individual Apatite minerals are:
Fluorapatite - Ca₅(PO₄)₃F
Chlorapatite - Ca₅(PO₄)₃Cl
Hydroxylapatite - Ca₅(PO₄)₃OH

Composition

Apatite group - Calcium fluoro-chloro-hydroxyl phosphate

Common Individual Group Members:
Fluorapatite - Calcium fluoro-phosphate
Cholorapatite - Calcium chloro-phosphate
Hyldroxylapatite - Basic calcium phosphate

Variable Formula

(Ca,Sr,Pb,Y,Mn,Na)₅(PO₄,AsO₄,SO₄,CO₃)₃(F,Cl,OH)

Color

Colorless, white, yellow, brown, gray, red, pink, purple, blue, green. Some specimens are multicolored.

Streak

White

Hardness

5

Transparency

Transparent to translucent

Specific Gravity

3.1 - 3.2

Luster

Vitreous

Cleavage

Indiscernible

Fracture

Conchoidal

Tenacity

Brittle

Other ID Marks

1) Specimens from certain localities will fluoresce orange yellow in shortwave ultraviolet light.
2) Thermoluminescent bluish-white.

Complex Tests

1) May become fluorescent orange-yellow in longwave ultraviolet light after heating.
2) Dissolves in hydrochloric acid.

In Group

Phosphates; True Phosphates; Apatite Group

Striking Features

Hardness and crystal form

Environment

As gemmy crystals in granite pegmatites; in hornfels in contact metamorphic rocks; in igneousdiabase environments; in ore veins, and in nepheline syenite pegmatites.

Rock Type

Igneous, Metamorphic

Popularity (1-4)

2

Prevalence (1-3)

1

Demand (1-3)

1