NEPTUNITE

 

Neptunite is a scarce, moderately complex sodium potassium lithium iron manganese titanosilicate mineral (Na2KLi(Fe,Mn)2Ti2Si8O24).  It has a nonmetallic, slightly glassy luster, a blackish color (actually, it's an exceedingly dark reddish black), and a reddish-brown streak.  Its crystals commonly occur as elongated, squarish rods.  It has a hardness of between 5 and 6, and it breaks along cleavage planes meeting at 80¡ and 100¡.  Neptunite can be an igneous or metamorphic mineral.

 

Neptunite (18 mm across) on blueschist (glaucophane metamorphite), associated with natrolite (white).  Dallas Gem Mine, San Benito County, California, USA.

 


 

Photo gallery of neptunite

 


 

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