Sulfur (Dominica, eastern Caribbean)
Volcanic sulfur from the island of Dominica in the eastern Caribbean Sea. (5.2 cm across at its widest)
A mineral is a naturally-occurring, solid, inorganic, crystalline substance having a fairly definite chemical composition and having fairly definite physical properties. At its simplest, a mineral is a naturally-occurring solid chemical. Currently, there are over 5200 named and described minerals - about 200 of them are common and about 20 of them are very common. Mineral classification is based on anion chemistry. Major categories of minerals are: elements, sulfides, oxides, halides, carbonates, sulfates, phosphates, and silicates.
Elements are fundamental substances of matter - matter that is composed of the same types of atoms. At present, 118 elements are known (four of them are still unnamed). Of these, 98 occur naturally on Earth (hydrogen to californium). Most of these occur in rocks & minerals, although some occur in very small, trace amounts. Only some elements occur in their native elemental state as minerals.
To find a native element in nature, it must be relatively non-reactive and there must be some concentration process. Metallic, semimetallic (metalloid), and nonmetallic elements are known in their native state.
Sulfur makes up way less than 1% of the Earth's crust, but it is not valuable. Elemental sulfur is frequently found at or near volcanic vents and fumaroles. Significant concentrations of sulfur occur in the Gulf of Mexico subsurface (Louisiana-Texas area). Sulfur has a nonmetallic luster and a bright canary-yellow color (when heated to a liquid, it becomes reddish-orange). It is fairly soft, lightweight, brittle, lacks cleavage, and has a distinctive scent.