Lazulite

Lazulite near Rapid Creek, Yukon, Canada Miniature, 5.4 x 5.1 x 2.4 cm © irocks “irocks.com”

Chemical Formula: (Mg,Fe2+)Al2(PO4)2(OH)2
Locality: Werfen, Salzburg, Austria
Name Origin: From the Arabic azul – “sky” and the Greek lithos – “stone.”

Lazulite ((Mg,Fe2+)Al2(PO4)2(OH)2) is a blue, phosphate mineral containing magnesium, iron, and aluminium phosphate. Lazulite forms one endmember of a solid solution series with the darker iron rich scorzalite.

Lazulite crystallizes in the monoclinic system. Crystal habits include steep bipyramidal or wedge-shaped crystals. Lazulite has a Mohs hardness of 5.5 to 6 and a specific gravity of 3.0 to 3.1. It is infusible and insoluble.

History

Discovery date : 1795

Optical properties

Optical and misc. Properties : Subtranslucent to opaque
Refractive Index : from 1,61 to 1,64
Axial angle 2V: 69°

Physical Properties

Color: Blue, Blue green, Light blue, Black blue.
Density: 3 – 3.1, Average = 3.05
Diaphaneity: Subtranslucent to opaque
Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern.
Hardness: 5-6 – Between Apatite and Orthoclase
Luminescence: Non-fluorescent.
Luster: Vitreous (Glassy)
Streak: white

Photos:

Lazulite Near Rapid Creek, Yukon, Canada Miniature, 3.9 x 3.0 x 1.9 cm © irocks ” irocks.com”
Lazulite, siderite and quartz Rapid Creek – Dawson Mining distr. – Yukon Territory – Canada Specimen weight:66 gr. Crystal size:mm. 7 Overall size: 55mm x 26 mm x 17 mm © minservice
Graves Mountain, Lincoln Co., Georgia, USA © 2001 John H. Betts
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