Pekoite is a comparatively rare mineral that belongs to the rare sulfate mineral category. It typically forms as an evaporite mineral in desert environments or as a result of volcanic activity. Its chemical composition is often reported as (Cu+,Cu2+)2Pb22+(VO4)(OH)2 and its formula is commonly expressed as Cu6Pb(bi)2(Bi,Sb)25S2O58Cl7. Pekoite crystallizes in the monoclinic crystal system, and its crystals are usually elongated and prismatic.
The mineral is named after its discovery location, the Peko mines in Tennant Creek, Northern Territory, Australia, where it was first identified in 1977. Pekoite typically appears as an opaque or translucent mineral, exhibiting a range of colors including green, blue-green, gray, and brown. It has a vitreous to greasy luster, and its hardness is approximately 4.5 on the Mohs scale.
Pekoite is commonly found associated with other minerals, such as bismuthinite, cassiterite, pyrite, and quartz. Its occurrence is relatively limited geographically, with notable occurrences reported in Australia, Namibia, Tajikistan, and Kazakhstan.
Due to its scarcity and restricted distribution, pekoite is primarily of interest to mineralogists and collectors. Its unique crystal structure and composition make it a fascinating specimen for research purposes, providing insights into geological processes and the formation of sulfates in specific environments.
