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Andalusite var. chiastolite

#AH51567

Andalusite var. chiastolite

#AH51567
Availability
Sold
Size
10 x 6 x 3.5 cm - Cabinet 
Formula
Al2OSiO4 (RRUFF)
Locality
Lancaster, Worcester Co., Massachusetts, United States

Chiastolite is a variety of Andalusite containg graphite inclusions giving it the cross patterns. As the Andalusite forms during metamorphism, the graphite aligns in cross-shaped patterns. Indeed this specimen consist of mostly graphitic schist.

This specimen was aquired by Hampson in 1944. The cross-sections are polished cuts in the andalusite to expose the crystals. 

Andalusite

Formula
Al2OSiO4 
Crystal System
Orthorhombic 
Crystal Habit
Blocky, Prismatic, Euhedral Crystals 
Cleavage
Distinct, Indistinct, Poor 
Luster
Vitreous (Glassy) 
Color
dark green, gray, brown, red, green 
Streak
white 
Class
Orthorhombic - Dipyramidal 
Fracture
Splintery 
Hardness
6.5-7 

Data courtesy of Webmineral.

Collection
Arnold G Hampson Collection

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