Specularite
Image: <a href="//commons.wikimedia.org/wiki/User:Islam90" title="User:Islam90">Islam90</a> (CC BY-SA 4.0)
Mineral NameSpecularite
Chemical FormulaFe2O3
Mohs Hardness5.5
Crystal Systemtrigonal
Lustermetallic
Streak Colorreddish-brown
Cleavagenone (parting on {0001} and {1011})
Fractureuneven
Specific Gravity5.26
Colorsdark gray, black, silvery
Transparencyopaque
Type LocalityWorldwide, notable occurrences include the Lake Superior region (USA), Brazil, and Elba (Italy)
Mineral GroupOxides
Usesiron ore, pigment, collector specimens
Associated Mineralsquartz, magnetite, jasper, goethite
Raritycommon
Description
The image shows a microscopic view of specularite, characterized by its aggregate of shiny, elongated, platy crystals that reflect light brightly, appearing as silvery streaks against a darker matrix.
Geological Context
Specularite is a variety of hematite, an iron oxide mineral, commonly found in metamorphosed banded iron formations (BIFs), hydrothermal veins, and as a primary mineral in some igneous rocks. It forms under conditions where iron-rich fluids or sediments are present.
