What is Krennerite?
Krennerite is a dense gold telluride ore mineral with metallic colour and high scientific value in the study of epithermal gold deposits.
Mineralogy and crystal structure
Reference formula: AuTe2. Krennerite has an orthorhombic AuTe2 structure and forms compositional relationships with calaverite and sylvanite. Its heavy, soft metallic grains should be identified by analysis or ore microscopy rather than appearance alone. Krennerite is classified with sulfides and has a orthorhombic crystal system. Typical hardness is 2.5–3 on the Mohs scale and specific gravity is approximately 8.6–9.0.
Colour, lustre and habit
Typical colours include silver-white, brass-yellow, grey, black. The usual tabular, granular, massive habit and metallic lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Krennerite forms in or is associated with low-temperature hydrothermal veins and telluride-rich gold deposits. Important documented localities include Romania, the United States, Canada, Australia, Fiji and Indonesia.
A high-density mineral with a precious-metal connection
Krennerite appeals to collectors because a small, unassuming metallic grain can represent an entire gold-telluride vein system. It is best shown with its associated quartz, sulfides and host rock, where the paragenesis adds value to the display.
Collecting and care
Telluride-bearing ore: keep labelled, avoid dust and cutting, wash hands after handling and do not use as jewellery material.
