| | + | The '''simple oxides''' are [[compounds]] of [[metallic]] [[elements]] with [[oxygen]]. They are called simple oxides because of their simple [[crystal structure]] and [[chemical composition]]. [[Water]], [[hydrogen]] [[oxide]] (i.e. [[ice]]), is a [[mineral]], and the commonest of all. This mineral group shows great range of [[hardness]] and [[color]]; some are [[opaque]], others are [[transparent]]. Some are [[rare]] [[gems]], and others are important [[ores]]. The simple oxides show similar variation in their origins, some of them forming deep in the [[earth's crust]], and others developing at shallow depths or even on the surface. Chesterman, p. 393 |