Molybdite

Molybdite
Molybdite on molybdenite from the Questa Molybdenum Mine (size: 11.0 x 6.7 x 4.1 cm)
General
Category	Mineral
Formula (repeating unit)	MoO3
IMA symbol	Myb[1]
Strunz classification	4.EA.10
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pbnm
Unit cell	a = 3.96 Å, b = 13.85 Å, c = 3.69 Å; Z = 4
Identification
Color	Light greenish yellow to nearly colorless
Crystal habit	Flattened needles or thin plates may occur in aggregates
Cleavage	Perfect on {100}, district on {001}
Tenacity	Flexible
Mohs scale hardness	3 - 4
Luster	Adamantine
Streak	White
Diaphaneity	Transparent
Specific gravity	4.72
Optical properties	Biaxial (+)
Birefringence	High
2V angle	Large
References	[2][3][4][5]

Molybdite is the naturally occurring mineral form of molybdenum trioxide MoO₃. It occurs as yellow to greenish needles and crystallizes in the orthorhombic crystal system.

Discovery and occurrence[]

Molybdite was first described in 1854 for and occurrence in quartz veins in the area of Krupka, Krušné Hory Mountains in the Ústí Region of Bohemia, Czech Republic.^[4] It occurs in vein cavities and as coatings in molybdenite ore veins and quartz topaz greisens. Associated minerals include molybdenite, and quartz.^[3] The similar mineral ferrimolybdite is often misidentified as molybdite.^[3]

References[]