Laetust

Laetust is a rare and distinctive mineral species, first discovered in the late 19th century. It is a complex borate mineral, with the chemical formula Na2B4O7(OH)4. Laetust is typically found in the form of white, acicular crystals, which can grow to significant sizes. It is often associated with other borate minerals, such as ulexite and borax, in evaporite deposits.

The mineral was named after the Latin word "laetus," meaning joyful or glad, reflecting its rarity and the delight it brings to mineral collectors. Laetust is relatively soft, with a Mohs hardness of 2.5, and has a specific gravity of approximately 2.2. It exhibits a vitreous luster and is typically colorless or white, although it can sometimes display a faint pink or blue tint due to impurities.

Laetust is primarily of interest to mineral collectors and researchers due to its rarity and unique crystal structure. It is not known to have any significant industrial applications. The mineral's formation is closely linked to the evaporation of brine lakes, where the concentration of borate ions leads to the precipitation of laetust crystals. Notable occurrences of laetust include the Boron Mine in California, USA, and the Searles Lake in California, USA.