Aragonite

A truly interesting brown mineral, especially in its ‘sputnik’ form. The unusual shape and pattern of the crystals makes it an excellent display object.

Aragonite also occurs in a banded brown and yellow colour which is often carved or cut.

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Appearance, Uses and History

Amongst the most common occurrences of Aragonite is as a constituent of shells – nacre is comprised of Aragonite.

The iridescent surface of mother of pearl and iridescent Ammonites from Madagascar is, in fact, a thin layer of Aragonite secreted by molluscs. This means Aragonite can be formed by both biological and physical processes.

Aragonite is a beloved mineral specimen for collectors, due to the varied colours and crystal formations it can form in. One of the most popular is the ‘sputnik’, a twinned, radiating form which was named after the Russian satellite.

Aragonite is too soft for most jewellery usage, although it is sometimes sold as beads or cabochons. Any jewellery designed using this stone should be designed to protect the stone. Pieces are very rarely faceted, although they are quite small and purely collectors specimens.

Locales

Aragonite has a worldwide distribution, with fine crystalline specimens found in Australia, Austria, Belgium, Bulgaria, Chile, China, France, Greece, Hungary, Italy, Madagascar (as iridescent Ammonite layers), Mexico, Morocco, New Zealand, Peru, Portugal, Romania, Russia, Slovakia, South Africa, Spain, the UK, the USA, and Vietnam.

Mineralogy

Chemistry
A form of Calcium Carbonate with the chemical formula CaCO3.
Colours and Variations
Often reddy brown, clear, yellow, orange, grey, off grey. Rarely specimens are blue, green.
Streak
White
Luster
Vitreous, resinous
Fracture
Subconchoidal
Transparency
Transparent, translucent
Crystal habit
Orthorhombic crystals, with pseudo hexagonal formations. Crystals are often acicular, massive, columnar, fibrous, coralloidal. Twinning is common.
Mohs hardness
3.5 – 4.0
Specific Gravity
2.92 – 3.0
Easiest testing method
Often fluoresces under UV light.
Common Treatments

Hazards and Warnings

 

Almost all rocks, minerals (and, frankly, almost all other substances on earth) can produce toxic dust when cutting, which can cause serious respiratory conditions including silicosis.
When cutting or polishing rocks, minerals, shells, etc, all work should be done wet to minimise the dust, and a suitable respirator or extraction system should be used.

Translations

Arabic:

  • أراجونيت

Hindi:

  • एंरेगोनाइट

Portuguese:

Bengali:

  • আরাগোনাইট

Indonesian:

  • aragonit

Punjabi:

English:

Italian:

Russian:

  • арагонит

French:

Japanese:

  • アラゴナイト

Spanish:

  • aragonito

German:

  • Aragonit

Korean:

  • 아라고 나이트

Thai:

Gujurati:

Mandarin and Traditional Chinese:

  • 霰石

Urdu:

Further Reading / External Links