ROCK+TERMS

=// Glossary of Terms  //= ATTRIBUTES  when discussing a group of objects, the characteristics that all members of the group share. Attributes for the group of minerals are color, streak, hardness, etc. CLEAVAGE  the tendency in minerals to break in such a way that a smooth, more even surface results CONDUCTIVITY  the ability to serve as a channel or pathway for the flow of heat, sound, or electricity EROSION  the process by which weathered material is carried away by wind or water FRACTURE  the tendency in minerals and rocks to break in uneven, irregular directions GEOLOGIST  a person who studies the origin, history, and structure of the earth HARDNESS  the relative ability of a mineral to scratch or be scratched by another mineral or object IGNEOUS ROCK  a rock produced from molten rock called magma or lava LUSTER  the quality of a mineral with respect to its ability to reflect light MAGMA  molten material beneath or within the earth's crust from which igneous rock is formed METAMORPHIC ROCK  an igneous or sedimentary rock that has been chemically or structurally changed by heat or pressure MINERAL  a naturally occurring, inorganic substance of definite chemical structure that has specific identifiable characteristics PETROLOGIST  a person who studies the origin, composition, structure, and alteration of rocks ROCK  a combination of mineral matter of various compositions SEDIMENT  mineral or organic matter deposited by water, air, ice, etc SEDIMENTARY ROCK  a rock formed from sediment by pressure of water or other layers of sediment STREAK  the line of powder obtained by scratching or rubbing a mineral upon a hard, rough, white surface STREAK PLATE  a rough piece of white porcelain used by geologists to test the streak of minerals TEXTURE  the characteristic property of a mineral determined by how it feels; related to cleavage or fracture TRANSPARENCY  the capacity of a mineral to allow the passage of light through it    VALUES   the subsets of the attributes of a group of objects. Values of color are red, green, blue, etc. WEATHERING  breaking apart or chemically changing earth substances by some force