Crocoite is a rare lead and chromium secondary mineral. Its rarity, bright red color, and exceptional crystal forms have guaranteed its place as a prized collection mineral. Crocoite is the first historic source of chromium and natural yellow pigment - unfortunately highly toxic.
Molybdenite is the principal ore mineral of molybdenum and rhenium. It occurs widely in igneous and metamorphic rocks generated under high temperature conditions. Despite its lack of popularity and rare crystal forms, it is a very interesting and important industrial mineral.
Aragonite is the less known cousin of calcite. Despite the lack of popularity, aragonite crystals and stalactites are among the most aesthetically-pleasing mineral specimes. Aragonite is present in various hydrothermal environments and it is the principal component of mollusk shells, coral skeletons and pearls.
The Klondike (Yukon) Gold Rush holds the record as one of the shortest-lived mining booms ever, lasting a scant 2 years, from August 1896 to September, 1898, when it was undermined by the slightly longer-lived Nome (Alaska) Gold Rush (September 1898 to 1905).