Sassolite

Sassolite is a rare mineral that consists of hydrated sulfuric acid, with the chemical formula H2SO4·H2O. It represents the mineral form of sulfuric acid monohydrate and is most commonly found in volcanic fumaroles and other high-temperature, sulfur-rich environments where sulfur dioxide and steam condense to form acid vapors.

In hand specimens, sassolite crystals are typically colorless or white and transparent to translucent. They occur as acicular (needle-like) crystals, sometimes forming fibrous or radiating aggregates.

Occurrence and formation: Sassolite has been reported from several volcanic regions around the world, often in the immediate vicinity of fumaroles or vents. It may be found in association with native sulfur, sulfuric acid sprays, and other fumarolic minerals. Because it contains water of hydration, sassolite is highly soluble in water and is sensitive to environmental humidity.

Significance: Sassolite is notable for representing a mineral composed of a simple acid in solid form, illustrating the chemistry of volcanic gas condensates. Its occurrence helps characterize fumarolic systems and the vents where sulfur-bearing vapors cool and crystallize.