Hollandite

Vanadinite, Baryte, Hollandite Locality: Mibladen Mining District, Midelt, Khénifra Province,  Meknès-Tafilalet Region, Morocco Dimensions: 14.3 cm x 9.6 cm x 7.9 cm Photo Copyright © Rob Lavinsky & irocks

Chemical Formula: Ba(Mn4+6Mn3+2)O16
Locality: Manganese deposits of the Central Provinces of India.
Name Origin: Named for Thomas Henry Holland (1868-1947), Director of the Indian Geologic Survey.

Physical Properties of Hollandite

Color:  Grayish black, Black, Silver gray.
Density: 4.7 – 5, Average = 4.84
Diaphaneity: Opaque
Fracture: Brittle – Generally displayed by glasses and most non-metallic minerals.
Hardness: 4-6
Luminescence: Non-fluorescent.
Luster: Earthy (Dull)
Streak: black

Photo:

This sample of hollandite is displayed in the Smithsonian Museum of Natural History. The sample is about 8 cm across and is from Serra do Navio, Brazil.
Königsberg, Wolfstein, Palatinate, Rhineland-Palatinate, Germany © Peter Haas
Quartz with Hollandite Ambatofinandrahana – Madagascar Specimen weight:54 gr. Crystal size:Up to 2 mm Overall size: 30mm x 30 mm x 50 mm © minservice