Rutile
Rutile is one of the five forms of titanium dioxide (TiO2) found in nature. Titanium is a metal used for high tech alloys because of its light weight, high strength and resistance to corrosion.It derives its name from the Latin rutilus, red, in reference to the deep red color of some specimens when viewed by transmitted light..
Rutile has among the highest refractive indices of any known mineral and also exhibits high dispersion. Small rutile needles present in gems are responsible for an optical phenomenon known as asterism. Asterated gems are known as "star" gems.
One of the crystal forms that it takes is that of slender needles (acicular) embedded in large quartz crystals A beautiful stone produced by large inclusions of golden rutile needles in clear quartz is called rutilated quartz. Rutile can also form its own interesting and beautiful mineral specimens.
Chemistry: Titanium oxide, TiO2 ♦ Crystal: Tetragonal system ♦ Color: reddish-brown, red, yellowish, bluish, violet, black ♦ Luster: Adamantine ♦ Transparency: transparent to opaque ♦ Fracture: subconchoidal to uneven ♦ Moh's hardness: 6 to 6.5 ♦ Localities: Minas Gerais, Brazil, Swiss Alps, USA and some African localities.