Ilvaite on Quartz

Ilvaite – CaFe3+Fe2+2O(Si2O7)(OH)
Class: Silicates – Sorosilicates
Crystal System: Monoclinic
Hardness: 5.5-6
Orthoclase
Talc (1)Diamond (10)
Scratches glass. Harder than a steel knife.
Quartz – SiO2
Elements: Silicon, Oxygen
Class: Silicates – Tectosilicates
Crystal System: Hexagonal
Hardness: 7
Quartz
Talc (1)Diamond (10)
Very hard. Scratches glass and steel.
Origin: 2nd Sovetskii Mine, Dalnegorsk – Russia History: Ex Richard A. Kosnar Collection
Did you know?

Ilvaite is named for Elba, the Italian island of Napoleon's exile. Its black crystals interest physicists because heating them past a certain point reshuffles the crystal's own symmetry.

Pressing a quartz crystal makes it give off a precise electric beat, which is why it keeps time in nearly every watch and once tuned the radios of World War II, when good crystals were a strategic resource.