A mineral, by definition, is. . . 1  Inorganic, which means that it is not made by a living organism. 2  A solid. 3  Has a regular crystal structure. 4  Made by nature which means minerals are not made, directly or indirectly, from human activity. 5  Has a predictable chemical formula. A solid. 2  There is one unusual exception. 3  Native mercury is a mineral and is the only metal that is a liquid at normal temperatures. 4  Has a regular crystal structure.
Image:Cultural Heritage Agency of the Netherlands 20309407 - RCE. An A-frame house is an architectural house style featuring steeply-angled sides (roofline) that usually begin at or near the foundation line, and meet at the top in the shape of the letter A. An A-frame ceiling can be open to the top rafters.
Also called reference frame. Physics. a framework that is used for the observation and mathematical description of physical phenomena and the formulation of physical laws, usually consisting of an observer, a coordinate system, and a clock or clocks assigning times at positions with respect to the coordinate system. Origin of frame of reference.