Selenite (mineral) was filled with mineral-rich water that drove the crystals' growth. The largest of those crystals weighs 55 tons, is long, and is over 500,000 years old. Gypsum occurs on every continent and is the most common of all the sulfate minerals. Gypsum is formed as an evaporative mineral, frequently found in alkaline lake muds, clay beds, evaporated seas, salt flats, salt springs, and caves. It is frequently found in conjunction with other minerals such as, copper ores, sulfur and sulfides, silver, iron ores, coal, calcite, dolomite, limestone, and opal. Gypsum has been dated to almost every geologic age since the
Mineral alteration zircon to "crytolite" (a metamict zircon) with amount of radioactive components and time. In some circumstances, a mineral alters while maintaining its outer form known as a pseudomorph. Mineral alteration is distinctly different than the rock alteration process metamorphism. It also differs from weathering. However, these processes assist in mineral alteration. Some minerals are members of a solid solution series and are samples of a range of compositional changes in a continuum, and thus are not 'mineral alteration' products. A common oxidation example is when a natural ferrous iron mineral such as pyrite is oxidized to form goethite or other