Birnessite

Birnessite (Na_0.3Ca_0.1K_0.1Mn⁴⁺Mn³⁺O₄·1.5(H₂O)) is an mineral oxide of manganese along with calcium, potassium and sodium. It has a dark brown to black color with a submetallic luster. It is also very soft, with a hardness of 1.5. Birnessite is formed by precipitation in lakes, oceans and groundwater and is a major component of desert varnish and deep sea manganese nodules.

Additional recommended knowledge

Weighing the right way

What is the Correct Way to Check Repeatability in Balances?

Recognize and detect the effects of electrostatic charges on your balance

It was first described in 1956 and named for an occurrence in Birness, Aberdeenshire, Scotland.

References

• Mindat with location data
• Webmineral data
• Mineral Data Publishing - PDF