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Frequently-Used Geological Terms Part 52 Glossary Adapted from the Dictionary of Geological Terms M Mineral - A naturally-occurring, inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties. Those who include the requirement of crystalline form in the definition would consider an amorphous compound (having no real or apparent crystalline form), such as opal, to be a Mineraloid . Also refers to a naturally formed inorganic material such as a member of the mineral kingdom as opposed to the plant and animal kingdoms. Mineral Deposit - Amass of naturally-occurring mineral material, such as metal ores or nonmetallic minerals, usually of economic value, without regard to mode of origin. Accumulations of coal and petroleum may, or may not, be included Mineral Filler - A finely pulverized inert mineral or rock which is included in a man- ufactured product, such as paper, rubber, and plastics to help with hardness, smooth- ness, or strength. Common mineral fillers include asbestos, kaolin, and talc. Mineralization - The process by which a mineral or minerals are introduced into a rock, resulting in a potential or actual ore deposit. It is a general term and includes various types such as fissure filler, im- pregnation, or replacement. The term also refers to the processs of fossilization, in which the organic components are re- placed by inorganic material. Mineralizer - A gas or fluid which dis- solves, receives by fractionation, trans- ports, and precipitates ore minerals. This term is also used to describe a gas which is dissolved in magma, which aids in the concentration, transport, and precipitation of certain minerals, and in the develop- ment of certain textures as it is released from the magma by decreasing temper- ature or pressure. Mineraloid - A naturally-occurring, inor- ganic solid which does not exhibit crys- tallinity. Although it may have the outward appearance of a mineral, it does not have the ordered atomic structure required to meet the definition of a mineral. Some mineraloids also lack the definite chemical composition required to be a mineral. Look for more terms next month! The gemstone opal, reportedly named from the Roman word opalus and the Greek word opallios meaning to see a change of color, is considered a mineraloid. 21 WorldWide Drilling Resource ® JULY 2016