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.
In physics, a frame of reference (or reference frame) consists of an abstract coordinate system and the set of physical reference points that uniquely fix (locate and orient) the coordinate system and standardize measurements. In n dimensions, n+1 reference points are sufficient to fully define a reference frame. Using rectangular (Cartesian) coordinates, a reference frame may be defined with a reference point at the origin and a reference point at one unit distance along each of the n coordinate axes.