Andalusite is an aluminium nesosilicate mineral with the chemical formula Al2SiO5.
Andalusite is isomorphic with kyanite and sillimanite, being the lower pressure mid-temperature polymorph. Andalusite is a which forms under low pressure and low to high temperatures. The minerals kyanite and sillimanite are polymorphs of andalusite, each occurring under different temperature-pressure regimes.
Andalusite is orthorhombic crystal mineral with 6.5 – 7.5 hardness according to the Mohs hardness scale and 3.17 (+/- .04) Specific Gravity.
Refractive Index is 1.629-1.690. This biaxial mineral has colors such as Pink, violet, yellow, green, white, gray, colorless to pink or green.
sometimes It comes as microcrystalline (chiastolite), that time it shows anomalous optical properties like aggregate. This trichroic mineral Clear colored crystals can show strong pleochroism. also, it doesn’t show fluorescence under UV light. But, Sometimes Brown andalusites fluorescence in SW (short wave UV light ).
We can see uneven to subconchoidal fractures as physical properties.
Andalusite can be found in Sri Lanka, Madagascar, Austria Australia, Argentina, Brazil, Botswana, Antarctica, Belgium, Bulgaria, Canada Chile, China, Denmark, Poland, Finland, Georgia, Germany, Greece, Hungary, India, Indonesia, Ireland, Iran, Iraq, Italy, Japan, Malawi, Mexico, Mongolia, Morocco, Myanmar, Mozambique, New Zealand, North Korea, Norway, Peru, Papua New Guinea, Portugal, Romania, Romania, Russia, Slovakia, South Africa, Swaziland, Sweden, Suriname, Tanzania, Thailand, Tajikistan, Turkey, Uk, Ukraine, USA, Vietnam. Andalusite clear stones is found mostly in Sri Lanka, Brazil, Madagascar.
Sometimes, Fibrous inclusions in andalusites may create a chatoyant effect. However,andalusite cats eye is very rare.
