History · Geology
About Rapid Creek (Yukon)
Rapid Creek and the adjacent Big Fish River area in the Yukon Territory, Canada, is the world’s premier source of gem-grade lazulite — the deep-blue Mg-Al phosphate. The deposit was discovered in the 1960s and remains the species archetype for collector-quality lazulite.
Geology
The deposits are unusual phosphate-rich diagenetic concretions in Cretaceous iron-formations. Cold-temperature diagenesis produced gem-grade lazulite, augelite, vivianite, wardite and other rare phosphate species in nodular concentrations.
Notable Minerals
Lazulite (deep azure-blue prismatic gem-grade crystals — world-best), vivianite (large gem prismatic crystals, sometimes deep blue), siderite (host rhombs), wardite (greenish prismatic — type locality), augelite, quartz, goethite, marcasite. Rapid Creek lazulite-on-siderite is the species archetype.
Collector Notes
Yukon access is remote and seasonal; collector specimens are released sparingly. Rapid Creek lazulite is the species’ iconic display form.
