Hubnerite from Mundo Nuevo, La Libertad, Peru

Blocky lustrous black crystal grouping of Hubnerite 2.3 cm in size nestled beautifully amongst colorless mostly gemmy Quartz crystals. Completely crystallized all around with no points of attachment .

Per Wikipedia ...

Hübnerite is a rare mineral from the Wolframite family and considered to be one of the principle ores of tungsten.

It's from a family with only two end members and easier to explain the composition of the wolframite family since there is not enough data on Hübnerite itself.