Minerals are most commonly classified by the Dana system. Minerals are identified according to hardness, specific gravity, color, luster, streak, cleavage and crystal form.
The Dana system of classification was devised by Professor James Dana of Yale University in 1848. His system classified minerals according to their chemical composition. For example, a halide has Cl (chlorine), Br (bromine), F (fluorine) or I (iodine) at the end of its chemical formula.
A new Dana system of classification contains 78 different classes of minerals based on composition and then further classified by type and group. To be considered a mineral, a substance must be an inorganic, naturally formed solid, with a specific chemical formula and a fixed internal structure. To test whether something is a mineral, there are several identification tests to which the substance is subjected, including its resistance to scratching, its density in comparison to water, its color, the degree of light it reflects, the color of the powdered mineral, its breakage pattern and its crystalline form.
There are over 4,900 different types of minerals known in the world.Learn More
Hurricane Andrew began as a tropical wave that crossed the west coast of Africa into the tropical North Atlantic on August 14, 1992. Two days later, after it passed just south of the Cape Verde islands, the wave became a tropical depression. Tropical Storm Andrew formed August 17 and became a hurricane three days later due to vertical wind shear. The hurricane caused 23 deaths in the United States.Full Answer >
Basalt is crushed and used to pave roads. It is also used to provide ballast for railroads and as a building stone. It is used in sculpture and to make basalt fiber and rock wool. Basalt can also be cut into flags and polished and used as flooring material.Full Answer >
According to About.com, agate forms from the deposition of silica in aqueous solution at low water depths and relatively low temperatures. It is a form of chalcedony mineral, which is a mass of quartz composed of microscopic crystals. Its porous nature, relative to other forms of quartz, allows it to develop impurities that give it a variety of colors and patterns, making it a popular stone for use in jewelry.Full Answer >
Marble is a metamorphic rock formed from limestone. Changes in the limestone's chemical properties due to external forces can result in the creation of marble.Full Answer >