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 in the alpine environment is a perfect example, as the seven major cushion forming species in Tasmania are representative of five different families. The densely crowded shoots with a high degree of branching, restrict air movement and maintain a moist internal atmosphere within the cushion. This provides insulation against extreme temperature fluctuations and minimal wind disturbance. Another example of morphological convergence is the predominance of small-leaved species in alpine vegetation. Small needle-shaped leaves with a relatively large surface-area to volume ratio are efficient in rapid energy transfer and heat dispersion while retaining structural strength. Scleromorphy is a common feature amongst