Humpback Mountain, Hansen Creek area, Snoqualmie Mining District, King County, Washington, USAi

Regional Level Types
Humpback Mountain	Prospect (Active)
Hansen Creek area	Creek
Snoqualmie Mining District	Mining District
King County	County (Historical)
Washington	State
USA	Country

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Overview
Quartz crystals occur in several breccia zones on the northern and western slopes of Humpback Mountain. All significant amethyst from Hansen Creek comes from these zones.

The main (northern) zone on Humpback Mountain was originally exposed by roadcuts from logging in the 1950s and 60s. It spans FS 5510-120 to FS 5510-110 (2750ft to 3500ft in elevation), and peripheral zones extend hundreds of feet above and below these limits. This zone has the largest quartz crystals in the area, averaging around 4-6cm but reaching 20cm in some anomalous pockets. Some quartz crystal surfaces are dull, frosted, and pitted - but others are Alpine-like, with vitreous luster and fine striations.

Amethyst in this zone exclusively occurs as secondary growth, and habits can range from slender, long-stemmed scepters to tight aggregates of short, stubby scepter heads. Amethyst crystals of both morphologies typically range from 3-5cm, but have occurred up to 10-12cm.

The vast majority of the mineralization is quartz. Oxidized pyrite, siderite, and ankerite appear in pockets in certain zones. Quartz crystals here often feature inclusions of clinochlore and actinolite.

All breccia above 3100 feet in elevation is under private claim.

A little aside on the Garden Slug claim:
A small breccia zone/extension adjacent to the main Hansen Creek breccia, producing the only crystals on the north side of Humpback Mountain with significant smoky color, in both first-generation and scepter crystals. The quartz here is either of terrible quality, in chewed-up pockets once filled with pyrite/carbonate that rotted away, or of the best quality with full, vitreous luster on all faces, only rivaled by the top echelon of crystals from upper Middle Fork localities. Scepter stems tend to be longer here, and the amethyst color tends to be lighter. Crystals are more slender on average, including scepters - giving rise to long-stemmed, incredibly glassy, smoky-amethyst specimens that are some of the finest single scepters from Washington.

Inclusions here include the normal actinolite and clinochlore. Epidote inclusions are rare in the rest of the breccia, but are common here. Some "onegite" crystals with densely goethite-included surfaces occur here.

Pyrite is less oxidized and has higher integrity here - specimens often survive acid washing with good luster and attractive surface pitting reminiscent of some of the less altered pyrites from the Purple Hope claims on Green Ridge. Pyrite inclusions are not uncommon, either as amorphous shreds or as well-crystallized cubes or octahedrons.

This locality has been privately owned since the 1980s.

Other areas
The Banana Slug claim occurs on the western side of Humpback Mountain. It is much smaller, but produces cute thumbnail amethyst scepters with consistent color. Matrix pieces are rare.

Mineral List

16 valid minerals. 1 erroneous literature entry.

Rock Types Recorded