The mineral apatite

Chemical Formula

Apatite is a group of minerals, with the group formula Ca₅(PO₄)₃(F,Cl,OH)

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

Composition

Apatite group - Calcium fluoro-chloro-hydroxyl phosphate
Fluorapatite - Calcium fluoro-phosphate
Chlorapatite - Calcium chloro-phosphate
Hydroxyl-apatite - Basic calcium phosphate

Many impurities can be present, which may completely alter the formula and form individual minerals. See the Apatite group for more information.

Color

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

Streak

White

Hardness

Crystal Forms
and Aggregates

(Hexagonal) Apatite generally forms in well-shaped hexagonal crystals, which may be elongated or stubby. Also occurs as flat, tabular plates, columnar, in globular masses, acicular, grainy, stalactitic, and earthy. Most common in enormous beds of massive material, from which industrial phosphate is mined.

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 fluoresce orange yellow in shortwave ultraviolet light
2) Thermoluminescent bluish-white

Varieties

Manganapatite - Manganese-rich variety of Apatite

Collophane - Microcrystalline variety of botryoidal white Apatite.

In Group

Phosphates ; True phosphates ; Apatite group

All About

Apatite is a member of the Apatite group, a group of isomorphous hexagonal minerals. Apatite may be regarded as a single mineral, but is usually divided into three more minerals: Fluorapatite, Chlorapatite, and Hydroxylapatite. Since it is hard to distinguish between these minerals, and since they may partially replace each other, a distinction between them is rarely made, and they are simply called "Apatite". However, most Apatite is Fluorapatite, the most common member by far.

Apatite is the most common phosphate mineral, and is the main source of the phosphorus required by plants. The bones and teeth of most animals, including humans, are of the same material as Apatite.

Apatite is named from the Greek word apate, which means "deceit", since Apatite has a similar appearance to so many minerals.

Uses

Apatite is the main source of phosphorus. Phosphorus was previously extracted from crystalline Apatite, but nowadays is extracted from enormous deposits of Apatite-rich rock. Apatite is essential in the manufacture of phosphate fertilizers, and is very important in the chemical and pharmaceutical industries. Apatite is also a popular collectors mineral, and some transparent specimens are faceted for collectors.

Striking Features

Hardness and crystal form

Complex Tests

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

Popularity (1-4)

Prevalence (1-3)

Demand (1-3)

Distinguishing
Similar Minerals

Beryl, Tourmaline, Quartz, Olivine, and Phenakite - much harder
Calcite - softer (3)
Pyromorphite and Mimetite - slightly softer (3½ - 4), usually occur in distinct localities

Commonly
Occurs With

Quartz, Feldspar, Rutile, Magnetite, Nepheline, Leucite, Aegirine, Phlogopite, Cassiterite, Anatase

Noteworthy
Localities

Apatite is a common mineral, and fine localities are worldwide. Enormous deposits are in the Kola Peninsula, Russia, containing both crystals and botryoidal material. Some of the finest crystals came from Ehrenfriedersdorf, Saxony Germany, where they are blue to purple in color. Colorless, hexagonal crystals were found in the Tyrol, Austria, and excellent material from Panasqueira, Portugal. Deep blue crystals are found in Campo Formosa, Bahia, Brazil, and in Sri Lanka. Enormous deposits mined for industrial use exist in Nauru, Morocco, Algeria, Tunisia, Egypt, and Israel.
Perhaps the most famous specimens are the gemmy yellow crystals from Cerro del Mercado (near Ciudad Durango), Durango, Mexico. In Ontario, Canada, large greenish-brown crystals come from Wilberforce, Haliburton Co., and the Bancroft area. Also in Canada is Otter Lake, Quebec, where large crystals occur on a matrix of orange Calcite.
In the U.S., famous violet crystals come from the Mount Apatite area (Hebron), Androscoggin Co., Maine. Prismatic green crystals closely resembling Tourmaline is found in Mesa Grande, San Diego Co., California.

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Links

Picture Links

1. Yellow crystal from Mexico
2. Columnar crystals