VS
Name
—
(Y,U,Fe²⁺)(Ta,Nb)(O,OH)₄
Formula
—
Mineral Species
Entry type
—
Oxides & Hydroxides
Chemical class
—
Amorphous
Crystal system
—
5–5.5
Mohs hardness
—
5.7
Specific gravity
—
Gray
Streak
—
Submetallic to vitreous, greasy
Luster
—
{010}, indistinct
Cleavage
—
—
Space group
—
—
Structural group
—
Yttl-Y · Approved
IMA
—
1802
Named in
—
Black, brownish black, brown; red-brown to dark brown in transmitted light, may show zonation
Typical colors
—
Y · U · Fe · Ta · Nb · O · H
Elements
—