Quartz is mined naturally, but more commonly produced synthetically in large, long-faceted crystals. Quartz is positive birefringent. Be careful not to confuse terminology in this material, as "Fused Quartz" is often used to denote the glassy non-crystalline form better known as Silica.
Normal Quartz is Alpha Quartz and normally RH rotating. LH rotating is available on special order.
At temperatures >490°C, Crystal Quartz starts to revert to glassy state, a process which is complete by 530°C. At this time, as annealling is unlikely, fracture of component is probable.
REFERENCES:
(1)J.V.Atansoff and P.J.Hart, Phys. Rev. Vol.59, pp 85-96 1941
(2)A.W.Lawson, Phys. Rev. Vol 59, pp.838-839, 1941
WEBLINKS:
Webmineral.com - Has further information on Quartz Crystal.
Rockhoundingar.com - Has information regarding the handedness of Quartz crystals.
Washington University - Has articles on research into this material.
Quartz-Dyne Inc. - Has information regarding Alpha Quartz.
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