Water is not classified as a mineral, since it lacks a
crystal structure being that it is in a liquid form. Many
scientific groups and references, including the acclaimed Dana's System
of Mineralogy, categorize
mineraloids such as
Opal and
Mercury together with the "true" minerals. However, virtually all mineral reference guides, including Dana's, exclude water from being classified as a mineral. (When water solidifies and turns into
Ice, however, it is considered a mineral by all accounts.) We have included water in thus guide for the purpose of delineating its properties so that it can be compared to the true minerals. Water and
Mercury are the only two naturally occurring,
inorganic substances with a definitive
chemical formula that occur in a liquid state at normal
temperatures.
Water covers more than 3/4 of the earth's surface, and is its most common and vital resource. It is a major solvent, dissolving more substances than any other liquid. For this reason, water is almost always
impure.
