Kroehnkite is a rare, blue-green mineral that belongs to the group of secondary copper sulfate minerals. It is an authentic sulfate mineral, with a chemical composition represented by the formula Na2Cu(SO4)2(H2O)2. The mineral gets its name from George L. Kroehnke, an American geologist, who discovered and first described it in 1959.
Kroehnkite typically crystallizes in the monoclinic crystal system and often forms as aggregates or crusts of tabular or prismatic crystals. It can also occur as fibrous masses or powdery coatings on other minerals within copper deposits. The mineral has a distinct vitreous to silky luster, and its color ranges from pale blue to bluish-green.
In terms of its occurrence, kroehnkite is usually found in oxidized portions of copper ore deposits, where it forms as a weathering product. It is typically associated with other minerals such as azurite, malachite, and chalcanthite. Kroehnkite is mainly found in a few known localities worldwide, including the Copper Queen Mine in Arizona, USA, and the Mammoth Mine in Tiger, Arizona.
Due to its rarity and attractive blue-green color, kroehnkite is often sought after by mineral collectors. Its aesthetic appeal and distinctive crystal habits make it an intriguing addition to mineral collections. However, given its limited occurrence and small crystal sizes, kroehnkite is considered a relatively scarce and lesser-known mineral within the realm of mineralogy.
