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2. Pegmatite - Wikipedia

   en.wikipedia.org/wiki/Pegmatite

   Pegmatite. A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than 1 cm (0.4 in) and sometimes greater than 1 meter (3 ft). Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic composition to granite.

3. Quartz - Wikipedia

   en.wikipedia.org/wiki/Quartz

   Quartz is, therefore, classified structurally as a framework silicate mineral and compositionally as an oxide mineral. Quartz is the second most abundant mineral in Earth's continental crust, behind feldspar. [10] Quartz exists in two forms, the normal α-quartz and the high-temperature β-quartz, both of which are chiral. The transformation ...

4. Luminous gemstones - Wikipedia

   en.wikipedia.org/wiki/Luminous_gemstones

   The first theme is using legendary luminous gems to illuminate buildings, for navigation lights on ships, or sometimes as guiding lights for lost persons (Ball 1938: 498–500). In India, the earliest country in which fine gemstones were known, belief in luminous gems dates back some twenty-five centuries.

5. Lepidolite - Wikipedia

   en.wikipedia.org/wiki/Lepidolite

   Lepidolite. Pink, light purple, purple, rose-red, violet-gray, yellowish, white, colorless other colors possible but are rare. Lepidolite is a lilac -gray or rose-colored member of the mica group of minerals with chemical formula K (Li,Al)3(Al,Si,Rb)4O10(F,OH)2. [2][3] It is the most abundant lithium -bearing mineral [4] and is a secondary ...

6. Quartzite - Wikipedia

   en.wikipedia.org/wiki/Quartzite

   Quartzite is a very hard rock composed predominantly of an interlocking mosaic of quartz crystals. The grainy, sandpaper-like surface is glassy in appearance. Minor amounts of former cementing materials, iron oxide, silica, carbonate and clay, often migrate during recrystallization, causing streaks and lenses to form within the quartzite. [1 ...

7. Asterism (gemology) - Wikipedia

   en.wikipedia.org/wiki/Asterism_(gemology)

   The star-effect may be also caused by the inclusions of hematite. In black star sapphire hematite needles formed parallel to the faces of the second order prism produce asterism. Some star sapphires from Thailand contain both hematite and rutile needles forming a 12-ray star. [3] Star-stones were formerly regarded with much superstition. [1]