Andalusite

1. Introduction
The andalusite is  one of the mineral kyanite, this kind of mineral includes andalusite, sillimanite and kyanite which the three ones have the same chemical composition(Al2O3.SiO2), but have different crystal structure, so have the slight different physics property. The andalusite chemical composition is Al2 [SiO4] O, the structural silicate mineral of island form that the crystal belongs to the perpendicularity (the oblique side). Usually the crystal takes the form of column, the cross section is close to the square. The color is pink, reddish brown or ashen, glass gloss, cylinder cleavage middling. Rigidity 6.5-7.5, specific gravity 3.15-3.16. The mullite be decomposed with the trait of extremely high fire-resistant when the andalusite under calcining at 1380 c. It is still very steady when heating to 1810 c,the volume does not swell, the mechanical intensity is very high; Chemical stability strong, don't dissolve all in sour. It is a kind of refractory material that can be used directly. Besides used in metallurgical industry, fine ceramic industry, can also smelt the light quality and high strength silicon aluminium alloy, make the direction wings of metallic fiber, supersound plane and spaceship. Other use can reference the introduction of cyanite which can use as gem with beautiful color and transparent one.

2. The chem. composition of andalusite as follows,
AL2O3:56.84-58.18%    SIO2:37.72-39.78%
FE2O3:0.19-0.78%   FEO:0.22-0.52%     CAO:0.12-0.29%
MGO:0.17-0.46%    K2O:0.09-0.11%    NA2O:0.04-0.08%
Our specification: 0.5-1.5mm, 0-1mm,1-3mm, 200meshes.