Rothoffite is a rare and specific mineral that belongs to the sulfate mineral group. It is categorized as a borate sulfate, consisting of boron in combination with sulfur and oxygen. The mineral was named after Axel Rothoff, a Swedish mineralogist, who discovered and described it in 1944.
Rothoffite is typically found in evaporite deposits, such as the evaporated mineral-rich waters of salt lakes or mineral springs. It forms as an efflorescent crust or as powdery masses with a monoclinic crystal structure. Its color ranges from white to pale yellow, and it usually appears transparent or translucent.
In terms of its physical properties, rothoffite has a moderate hardness on the Mohs scale, measuring approximately 3.5 to 4. Its density is relatively light, typically around 2.6 grams per cubic centimeter. The mineral also exhibits a vitreous to pearly luster, giving it a somewhat shiny appearance.
Chemically, rothoffite is composed of boron, sulfur, oxygen, and hydrogen. Its chemical formula is commonly written as NaCa[B5O9]·H2O, denoting its combination of sodium (Na), calcium (Ca), boron (B), sulfur (S), oxygen (O), and water molecules (H2O).
Due to its rarity and limited occurrence, rothoffite does not hold a significant economic value. However, it serves as an important mineral for scientific and mineralogical studies, contributing to our understanding of the geological processes involved in the formation of borate minerals.
