Bixbyite
Bixbyite is a manganese iron oxide mineral with the chemical formula (Mn,Fe)2O3. It forms black, metallic, cubic crystals, often twinned. It is named after Maynard Bixby (1853–1935), an American mineral collector and dealer, who first discovered it in 1897 at the Maynard's Claim in the Thomas Range, Juab County, Utah, USA.
Properties: Bixbyite is a hard and dense mineral with a Mohs hardness of 6.0 - 6.5 and a specific gravity ranging from 4.8 to 5.1. Its luster is metallic to submetallic. It is opaque and its streak is dark brown to black. The mineral exhibits no cleavage. Its fracture is uneven to conchoidal.
Occurrence: Bixbyite typically occurs in cavities within rhyolite lavas, associated with other volcanic minerals like topaz, spessartine garnet, pseudobrookite, and hematite. It can also be found in manganese-rich metamorphic rocks. Significant occurrences include the Thomas Range in Utah, the Sierra de Comechingones in Argentina, and various locations in Mexico, India, and Germany.
Distinguishing Characteristics: Bixbyite can be distinguished from similar minerals, such as magnetite and franklinite, by its cubic crystal habit and its association with specific volcanic environments and mineral assemblages. Its reddish internal reflections under strong light may also be a distinguishing characteristic.
Uses: Bixbyite is primarily of interest to mineral collectors. It does not have significant industrial applications due to its relative rarity.
Related Minerals: Bixbyite can be associated with, and sometimes confused with, other manganese and iron oxide minerals such as braunite, hausmannite, and hematite.
Note: There exists a beryllium aluminum cyclosilicate mineral named Bixbite, often referred to as Red Beryl. This is a separate and distinct mineral species from Bixbyite, the manganese iron oxide.