<Table> <Tr> <Th_colspan="2"> Topaz </Th> </Tr> <Tr> <Td_colspan="2"> Topaz crystal on white matrix </Td> </Tr> <Tr> <Th_colspan="2"> General </Th> </Tr> <Tr> <Th> </Th> <Td> Nesosilicate minerals </Td> </Tr> <Tr> <Th> Formula (repeating unit) </Th> <Td> Al SiO (F, OH) </Td> </Tr> <Tr> <Th> Strunz classification </Th> <Td> 9. AF. 35 </Td> </Tr> <Tr> <Th> Crystal system </Th> <Td> Orthorhombic </Td> </Tr> <Tr> <Th> Crystal class </Th> <Td> Dipyramidal (mmm) H-M symbol: (2 / m 2 / m 2 / m) </Td> </Tr> <Tr> <Th> Space group </Th> <Td> Pbnm </Td> </Tr> <Tr> <Th> Unit cell </Th> <Td> a = 4.65 Å, b = 8.8 Å, c = 8.4 Å; Z = 4 </Td> </Tr> <Tr> <Th_colspan="2"> Identification </Th> </Tr> <Tr> <Th> Color </Th> <Td> Colorless (if no impurities), blue, brown, orange, gray, yellow, green, pink and reddish pink </Td> </Tr> <Tr> <Th> Crystal habit </Th> <Td> Prismatic crystals with faces striated parallel to long dimension; also columnar, compact, massive </Td> </Tr> <Tr> <Th> Cleavage </Th> <Td> (001) Perfect </Td> </Tr> <Tr> <Th> Fracture </Th> <Td> Subconchoidal to uneven </Td> </Tr> <Tr> <Th> Mohs scale hardness </Th> <Td> 8 (defining mineral) </Td> </Tr> <Tr> <Th> Luster </Th> <Td> Vitreous </Td> </Tr> <Tr> <Th> Streak </Th> <Td> White </Td> </Tr> <Tr> <Th> Diaphaneity </Th> <Td> Transparent </Td> </Tr> <Tr> <Th> Specific gravity </Th> <Td> 3.49--3.57 </Td> </Tr> <Tr> <Th> Optical properties </Th> <Td> Biaxial (+) </Td> </Tr> <Tr> <Th> Refractive index </Th> <Td> n = 1.606--1.629 n = 1.609--1.631 n = 1.616--1.638 </Td> </Tr> <Tr> <Th> Birefringence </Th> <Td> δ = 0.010 </Td> </Tr> <Tr> <Th> Pleochroism </Th> <Td> Weak in thick sections X = yellow; Y = yellow, violet, reddish; Z = violet, bluish, yellow, pink </Td> </Tr> <Tr> <Th> Ultraviolet fluorescence </Th> <Td> Short UV = golden yellow; Long UV = cream </Td> </Tr> <Tr> <Th> References </Th> <Td> </Td> </Tr> </Table> <Tr> <Th_colspan="2"> Topaz </Th> </Tr> <Tr> <Td_colspan="2"> Topaz crystal on white matrix </Td> </Tr> <Tr> <Th_colspan="2"> General </Th> </Tr>

Where is topaz found in the united states