Quartz (Silicate-Framework)
SiO2Hardness: 7.0
Specific Gravity: 2.65
Characteristics: Often white, sometimes colorless, purple, red, blue, yellow, or other colors; vitreous luster; conchoidal fracture; may contain fibrous needles of rutile; only soluble in HF.
A very common mineral found in igneous rocks, many metamorphic rocks, and most sedimentary rocks.
As a crystal or in cryptocrystalline form, quartz is used as a decorative stone in collections and jewelry. Quartz has many other uses such as in pressure guages, oscillators, resonators, and wave stabilizers. Due to the mineral's optical characteristics it is used in heat-ray lamps, prisms, and spectrographic lenses. Also used in the manufacture of glass, paints, and abrasives.
(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)