Chiastolite

Chiastolite is a variety of Andalusite which carries a distinct ‘cross’ pattern, formed by inclusions of black Carbon.

As it naturally has an extremely unusual pattern, it is often used for jewellery making. It was distributed by pilgrims in the 16th century due to this pattern.

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Appearance, Uses and History

Chiastolite is a variant of opaque Andalusite with a very distinct cross shaped inclusion of Graphite.

During the 16th century this stone was distributed around Europe by pilgrims returning from Spain due to its obvious symbolism related to the Christian faith.

Locales

The best locale for Chiastolite is in Spain, the Asturias region.

It also occurs in Australia, China, France, Portugal, and the USA.

Mineralogy

Chemistry
An opaque variety of Andalusite – Al2SiO5
Colours and Variations
White, grey, yellowish, pinky-brown, black.
Streak
White
Luster
Vitreous
Fracture
Uneven, splintery
Crystal habit
Orthorhombic
Mohs hardness
5.0 – 5.5
Specific Gravity
3.00 – 3.15
Easiest testing method
Visual inspection – dark graphite cross is easily identified.
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:

Hindi:

Portuguese:

  • quiastolito

Bengali:

Indonesian:

Punjabi:

English:

Italian:

Russian:

French:

Japanese:

  • キアストライト

Spanish:

  • quiastolita

German:

  • Chiastolit

Korean:

Thai:

Gujurati:

Mandarin and Traditional Chinese:

Urdu:

Further Reading / External Links