The Hycroft deposit is a low sulfidation, epithermal, hot springs system that contains gold and silver mineralization.
Regional Geology
The Hycroft Mine is located on the western flank of the Kamma Mountains in the Basin and Range physiographic province of northwestern Nevada. The faults served as conduits of hydrothermal fluids that deposited the Hycroft mineralization.
Local Geology
The deposit is typically broken into six major zones based on geology, mineralization, and alteration. These include Brimstone, Vortex, Central, Bay, Boneyard, and Camel. The boundaries are typically major faults, namely Break, East and Ramp.
Brimstone
The stratigraphy at Brimstone includes up to 100 feet of alluvium, underlain by Camel Conglomerate rocks (0 feet to 400 feet). The Brimstone ore deposit is hosted primarily by Kamma volcanic rocks in the hanging wall of the East Fault.
At Brimstone, the East Fault is a north-northeast striking, west dipping, normal fault with repeated episodes of movement, including approximately 150 feet to 200 feet of alluvial offset. Where exposed in the Brimstone Pit, the fault clearly shows steep normal movement, with slickensides that plunge 80º to 85º. At depth the fault shallows to 45° to 60º and may merge with the Central and Break Faults. Only minor mineralization is noted footwall to the fault zone.
Zones of silicification of limited thickness, oriented parallel to the East Fault ........