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 tax Mineral tax A mineral tax is any tax, excise or other government-imposed fee on mineral resources, such as crude oil or ores. The taxation of minerals serves as a price to extract scarce resources, such as petroleum and crude oil, which are owned by the government. By taxing minerals, the government is able to secure a certain share of the minerals. Mineral taxes should possess neutral characteristics, to maintain incentives for investors and maximize the tax revenue for the government, while minimizing the variability and uncertainty of the amount of tax money collected. Since the 1950s it is more common