The Rare and Fascinating Mineral Bacillite: Formation, Properties, and Occurrences

Bacillite is a type of mineral that is formed through the chemical precipitation of calcium carbonate (CaCO3) from solution. It is a relatively rare mineral that is found in only a few locations around the world, including some caves and mines.

Bacillite is named for its distinctive rod-shaped crystals, which resemble bacteria. The crystals are typically yellow or orange in color and can range in size from a few millimeters to several centimeters. Bacillite is a soft mineral, with a Mohs hardness of only about 2.5, which means that it can be easily scratched or broken.

Bacillite is formed when calcium carbonate is precipitated out of solution, often as a result of changes in the water chemistry or the presence of other minerals. It can be found in a variety of geological settings, including limestone caves, marble deposits, and hydrothermal veins.

Some of the most notable occurrences of bacillite are found in the United States, particularly in the states of Missouri and Arkansas. In these locations, bacillite is often found associated with other minerals such as calcite, dolomite, and quartz. It is also found in smaller quantities in other parts of the world, including Europe, Asia, and Africa.

Overall, bacillite is a unique and interesting mineral that is prized by collectors for its distinctive appearance and rarity.