Читать книгу Earth Materials онлайн

35 страница из 155

4 Every mineral species possesses a long‐range, geometric arrangement of constituent atoms or ions. This implies that the atoms in minerals are not randomly arranged. Instead minerals crystallize in geometric patterns so that the same pattern is repeated throughout the mineral. In this sense, minerals are like three‐dimensional wall paper. A basic pattern of atoms, a motif, is repeated systematically to produce the entire geometric design. This long range pattern of atoms characteristic of each mineral species is called its crystal structure. All materials that possess geometric crystal structures are crystalline materials. They are minerals, in the narrow sense, if they are naturally occurring, inorganic solids with a well‐defined chemical composition. Solid materials that lack a long‐range crystal structure are amorphous materials, where amorphous means without form and without a long‐range geometric order.

formed by inorganic processes

mineraloidsamorphous

rockmonominerallicpolyminerallic