Dolomite A carbonate mineral similar to calcite in which magnesium partially substitutes for calcium.

Drill Bit A tool that is placed on the end of a string of pipe to drill a well. Rotary drill bits are commonly used in oil and gas and geothermal drilling. Coring bits are used to obtain...

Drill Core Intact cylindrical shaped sample of rock obtained during drilling with a special coring bit. Although commonly narrow in diameter (e.g., 1-4" or 25-100 mm), it preserves a...