Twinning occurs when there is a small defect in the atomic bonding of the mineral causing the mineral to deviate from it's perfect form. This deviation results in penetration, repeated and contact mineral twins. Sulfides are typically opaque and characteristically colored with distinctive streaks. Those that are nonopaque have extremely high refractive indices and transmit light only on their edges. The majority of mineral ores are sulfides.
Sulfides are typically opaque, colored with distinctive streaks.
Sulfosalts are usually found as minor minerals in hydrothermal deposits and commonly contain lead, silver or copper. They are not commonly used as ores. In the small alcove you will find the Miniature mineral specimens. This case includes a selection of minerals from all the mineralogic classifications. Each of these minerals is a small but beautiful example of its species.