Physics

Chromite Definition Chromite is a brownish-black mineral consisting of a ferrous chromic oxide in cubic crystalline form, occurring principally in basic igneous rocks: the only…

Lava Tube Definition Lava tubes are the longest and most complicated of volcanic caves. They are the channels of rivers of lava that at some…

Volcanic Rock Definition Volcanic rock is an igneous rock of volcanic origin. It differs from other igneous rock by being of volcanic origin. Volcanic rocks…

Komatiite Definition Komatiite is relatively common in Archean greenstone belts, rare in Proterozoic belts, and virtually absent in younger regions. The type area is the…

Putnisite Definition The mineral, named putnisite, appears purple and translucent, and contains strontium, calcium, chromium, sulphur, carbon, oxygen and hydrogen, a very unusual combination. It…

Tourmaline Definition Tourmaline is Any of several minerals having the general chemical formula (Na,Ca)(Mg,Fe,Al,Li)3 Al6 (BO3)3 Si6 O18 (OH)4 . Tourmaline occurs in many different…

Spodumene Definition Spodumene is a greyish-white, green, or lilac pyroxene mineral consisting of lithium aluminium silicate in monoclinic crystalline form. It’s formula: LiAlSi 2O6. It…

Hypersthene Definition Hypersthene is a green, brown, or black pyroxene mineral consisting of magnesium iron silicate in orthorhombic crystalline form. It is a common rock-forming…

Beryl Definition Beryl is a usually green or bluish-green hexagonal mineral occurring as transparent to translucent prisms in igneous and metamorphic rocks. Transparent varieties, such…

Amethyst Definition Amethyst is a purple or violet, transparent form of quartz used as a gemstone. The color is caused by the presence of iron…

Amphibole Definition Amphibole is any of a large group of usually dark minerals composed of a silicate joined to various metals, such as magnesium, iron,…

Granite Definition Granite is a usually light-colored, coarse-grained igneous rock consisting mostly of quartz, orthoclase feldspar, sodium-rich plagioclase feldspar, and micas. This popular rock has…