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Melting point
1670°C
T<573°C
α-quartz
righthanded
& lefthanded
T>573°C
β-quartz
Mechanical
Q>106
Piezoelectric
Hyderothermal growth in H2O+NaCl (~1000 years) p≈1000bar
Both α forms present: righthanded & lefthanded (twinning)?
Impurities? Inclusions? Availability?