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
Alpine vegetation of Tasmania two gymnosperm families, Cupressaceae (Diselma archeri, Athrotaxis cupressoides, A. selaginoides) and Podocarpaceae (Michrocachrys tetragona, Microstrobos niphophilus, Podocarpus lawrencei). This vegetation type has a patchy distribution in areas topographically protected from fire. This vegetation would likely be the climax vegetation of the region in the absence of fire. Alpine heath is the most widespread, most diverse vegetation type in Tasmanian alpine environments. Many families are present however this vegetation is dominated by species from Ericaceae and Proteaceae. The diverse range of communities is distributed according to variation in soil conditions, drainage, exposure and fire history. Tall heaths with plants up to