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The Mineral Andalusite
andalusite picture

andalusite picture

Andalusite, a brownish or green brown mineral is an aluminium Nesosilicate.  It is a polymorph with two other minerals: Sillimanite and Kyanite. Andalusite is basically a lower pressure mid-temperature polymorph mineral. At high temperatures, it turns into Sillimanite. The crystal of the mineral Andalusite has an Orthorhombic structure and brittle tenacity. Chiastolite is a unique variety of Andalusite. It contains brown or black clay inside the crystal.

Occurrence

Andalusite can be found in several environments. They are located in regional metamorphosed schists, Hornfels and Gneisses rocks. They are also present in hydrothermal replacement deposits, alluvial deposits and in granite. Their Notable Occurrences include Spain, Andalusia, Austria, China, USA and California.

Derivation Of Name

In the year 1798, this nearly transparent to opaque mineral was given its name by Jean-Claude Delamétherie, who, along with Werner, analyzed this specimen from Spain and later called it as “Andalusite”. Andalusite is known for its location in Andalusia, Spain

Chemical Formula

Al2SiO5

 

Physical characteristics

  • Color: Red, reddish brown, olive-green. 

  • Luster. Dull or Vitreous

  • Transparency: varies between opaque and transparent

  • Fracture. Uneven or splintery

  • Associated minerals: Cordierite, Sillimanite Biotite, Quartz, Feldspars and Kyanite Specific gravity: 3.1 - 3.2

  • Hardness: 6.5 - 7.5 on the Mohs Scale

Applications

Andalusite is an opaque to nearly transparent mineral often associated with igneous  and metamorphic rocks. Andalusite possesses a vitreous characteristic, occurring in the colors such as violet, pink, yellow, green, gray and white. The application of Andalusite includes the production of refractory bricks, in making beautiful Andalusite jewelry and, in Feng Shui. This mineral falls under hard mineral and hence an ideal choice for jewelry designing. The beauty of this stone depends on its cutting and polishing. Different cutting shows its different luster and color shades. In Chinese Feng Shui system, it is believed that this stone brings harmony in the office and at home.


Mythical Uses

andalusite picture

andalusite picture

The mineral Andalusite is believed to increase eyesight and memory. It also assists in attaining moderation or enlightenment. This natural gemstone is known to bring balance to the wearer, also helps in centering and is highly beneficial for meditation.

Gemology

The transparent specimen of the Andalusite is used as a minor gemstone. Chiastolite: a variety of Andalusite, is often cut through its cross-sections and polished to bring out the best distinctive cross-shaped pattern. This can be used to craft rings, pendants, beads and earrings. It contains carbon in its cross-shaped.


 

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