Garnet

A gem or gemstone is either a mineral, rock or a petrified material that is valuable and is used in jewelry. Some types of gems are organic such as amber and jet. Gemstones that are too delicate for use in jewelry are kept for display at museums or are collected by enthusiasts.

The garnet is a type of gemstone with a habit of rhombic dodecahedrons and trapezohedrons. They are nesosilicates and their chemical elements include calcium, magnesium, aluminium, iron2+, iron3+, chromium, manganese, and titanium. They show no cleavage and a dodecahedral parting and fracture is conchoidal to uneven. Its hardness is 6.5 to 7.5, specific gravity is 3.1 to 4.3, and its lustre is vitreous to resinous. Garnets can vary from being transparent to opaque. The term 'garnet' is coined from the Latin word 'granatus', which means 'grain'. Generally, garnets found are red in color, they are however also found in a wide variety of colors such as purple, red, orange, yellow, green, brown, black, or colorless. The blue color-change garnets are some of the rarest garnets; they are a mix of spessartine, and pyrope. In daylight the colors of these garnets could be shades of green, beige, brown, gray and rarely blue, to reddish or purplish/pink color in incandescent light. Based on their chemical composition there are six common varieties of garnet these are pyrope, almandine or carbuncle, spessartite, grossularite (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series; 1. pyrope-almandine-spessarite and 2. uvarovite-grossularite-andradite.

Garnets in their purest crystallized form are used as gemstones. They are also abrasive, and are a regular replacement for silica sand that is used in sand blasting. Garnets mixed with pressurized water are used to cut steel and other materials.