Today for school, I had one assignment: "Identify the crystalline structures of several common and 'precious' gemstones you identified elsewhere, and the various types of bonding in them." Pretty easy, I though. And it was. Here is my list:
- Sapphires — Crystal Habit: have massive granular crystals. Crystal System: Trigonal Symbol (32/m) Space Group: R3c
- Topaz — Crystal Habit: Prismatic crystals with faces striated parallel to long dimension; also columnar, compact, massive. Crystal System: orthorhombic (“a crystal system or three-dimensional geometric arrangement having three unequal axes at right angles.”)
- Garnet — Crystal Habit: rhombic dodecahedra or cubic. Crystal System: Cubic rhombic dodecahedron, icositetrahedron
- Amethyst — Crystal Habit: 6-sided prism ending in 6-sided pyramid (typical). Crystal System: rhombohedral class 32
- Beryl — Crystal Habit: Massive to well Crystalline. Crystal System: Hexagonal (6/m 2/m 2/m) Space Group: P 6/mсc
- Ruby — Crystal Habit: Varies with locality. Terminated tabular hexagonal prisms. Crystal System: Trigonal (Hexagonal Scalenohedral) Symbol (−3 2/m) Space Group: R-3c
- Emerald — Crystal Habit: Massive to well Crystalline. Crystal System: Hexagonal (6/m 2/m 2/m) Space group: P6/mсc
Sources (all information is direct quotes):
http://en.wikipedia.org/wiki/Sapphire
http://en.wikipedia.org/wiki/Topaz
http://en.wikipedia.org/wiki/Garnet
http://en.wikipedia.org/wiki/Amethyst
http://en.wikipedia.org/wiki/Beryl
http://en.wikipedia.org/wiki/Ruby
http://en.wikipedia.org/wiki/Emerald
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