Neptunite
Chemical Formula	KNa2Li(Fe2+,Mn2+)2Ti2Si8O24
Species	Silicates
Crystal System	Monoclinic
Mohs Scale	5-6
Specific Gravity	3.19-3.23
Color	Black; deep red-brown in thin fragments
Streak	Brown to red brown
Luster	Vitreous
Refractive Index	n = 1.690 - 1.691 n = 1.693 - 1.700 n = 1.719 - 1.736
Diaphaneity	Opaque
Cleavage	Perfecton
Fracture	Conchoidal
Crystal Habit：Prismatic or tabular