...Lustre vitreous. Transparent to translucent on the edges. Exhibits trichroism in a remarkable degree. " On looking through a crystal in the direction of either...seen, interrupted at the point occupied by the axis." Fracture small, conchoidal. Becomes electric by friction or heat. The faces SILICA AND SILICATES. P,...

...Lustre vitreous. Transparent to translucent on the edges. Exhibits trichroism in a remarkable degree. " On looking through a crystal in the direction of either...seen, interrupted at the point occupied by the axis." Fracture small, conchoidal. Becomes electric by friction or heat. The faces P, /, u, r are usually...

...; highly vitreous. Colour ; clove-brown of various shades, inclining to plum-blue to pearl grey. It exhibits trichroism. On looking through a crystal...seen, interrupted at the point occupied by the axis (Miller). The acute bisectrix is negative, and normal to the plane x. The planes of the red and the...

...; highly vitreous. Colour ; clove-brown of various shades, inclining to plum-blue to pearl grey. It exhibits trichroism. On looking through a crystal...seen, interrupted at the point occupied by the axis (Miller). The acute bisectrix is negative, and normal to the plane x. The planes of the red and the...

...; highly vitreous. Colour ; clove-brown of various shades, inclining to plum-blue to pearl grey. It exhibits trichroism. On looking through a crystal...seen, interrupted at the point occupied by the axis (Miller). The acute bisectrix is negative, and normal to the plane x. The planes of the red and the...