APATITE
The mineral was named apatite by the German geologist Abraham Gottlob Werner in 1786, although the specific mineral he had described was reclassified as fluorapatite in 1860 by the German mineralogist Karl Friedrich August Rammelsberg. Apatite is often mistaken for other minerals. This tendency is reflected in the mineral’s name, which is derived from the Greek word ἀπατάω (apatáō), which means to deceive.
The town of Apatity in the Arctic North of Russia was named for its mining operations for these ores.
It is one of a few minerals produced and used by biological micro-environmental systems. Hydroxyapatite, also known as hydroxylapatite, is the major component of tooth enamel and bone mineral. A relatively rare form of apatite in which most of the OH groups are absent and containing many carbonate and acid phosphate substitutions is a large component of bone material.
They are also a proposed host material for storage of nuclear waste, along with other phosphates.
Moon rocks collected by astronauts during the Apollo program contain traces of apatite. Following new insights about the presence of water in the moon, re-analysis of these samples in 2010 revealed water trapped in the mineral as hydroxyl, leading to estimates of water on the lunar surface at a rate of at least 64 parts per billion – 100 times greater than previous estimates – and as high as 5 parts per million. If the minimum amount of mineral-locked water was hypothetically converted to liquid, it would cover the Moon’s surface in roughly one meter of water.
It is occasionally found to contain significant amounts of rare-earth elements and can be used as an ore for those metals. This is preferable to traditional rare-earth ores such as monazite, as apatite is not very radioactive and does not pose an environmental hazard in mine tailings. However, apatite often contains uranium and its equally radioactive decay-chain nuclides.
Blue Brazilian apatites and those with a “neon” blue-green color, similar to that of paraíba tourmalines, command the highest prices. Rare, rich purple specimens from Maine are also highly prized. Since apatites are relatively soft stones, skilled faceters can add a premium to their value with exceptional polishes.
Apatite can be prismatic, tabular, massive, compact, or granular.
USES
Its primary use is as a source of phosphate in the production of fertilizer.
It is sometimes used as a gemstone, but its hardness of 5 on the Mohs scale makes it too soft for widespread use in jewelry.
It is used as an ore of phosphate in many industries, including:
Pharmaceuticals
Ceramics
Silk
Textiles
Production of pure chemicals
Insecticides
Sugar refining
Manufacture of explosives
Ground apatite was used as a pigment in the Terracotta Army of 3rd-century BCE China, and in Qing Dynasty enamel for metalware.
MOHS HARDNESS
5
LUSTER
Vitreous (glassy) luster, meaning it reflects light like glass. Density: The density of apatite varies depending on the composition of the mineral, but it typically falls between 3.1 to 3.4 g/cm³.
CHEMICAL COMPOUND
Ca10(PO4)6(OH,F,Cl)2; this represents a group of phosphate minerals where the “X” position can be occupied by hydroxide (OH-), fluoride (F-), or chloride (Cl-) ions, with the most common forms being hydroxyapatite (OH), fluorapatite (F), and chlorapatite (Cl).
WHERE TO FIND
Major sources for gem quality are Brazil, Burma, and Mexico.
DIAGNOSTIC PROPERTIES
- Color: Can be colorless, yellow, blue, violet, pink, brown, or green
- Transparency: Can be transparent or translucent
- Fluorescence: The fluorescence varies by color
- Blue: Blue apatite fluoresces blue in both long and short wave
- Violet: Violet apatite fluoresces greenish yellow in long wave and light purple in short wave
- Yellow: Yellow apatite fluoresces purplish-pink, which is stronger in long wave
- Green: Green apatite fluoresces greenish-yellow, which is stronger in long wave
- Pleochroism: The pleochroism varies by color
- Colorless: Colorless forms has very weak to weak pleochroism