Minerals of the Humpback Mountain Slump Zone, Hansen Creek Area, Washington
If you can’t tell by my literal worship of the place all over this website, Hansen has to be one of my favorite localities on the planet. Public access points, ease of digging, and the quality of crystals are pretty much unmatched in King County. I’ll focus this article on the latter two - ease of digging (or WHERE minerals occur) and the quality/selection of various minerals.
Anyone who’s dug at Hansen will tell you that the dirt has crystals - in some areas, there’s more quartz than anything else in the soil! This is likely the result of a catastrophic landslide many millennia ago that shredded pockets open and spilled crystals all in the landslide debris. Because of this, crystals can have significant chips, fractures, and sometimes even rounded edges.
A lot of people ask me if I have a secret to navigating the melting pot of crystals that is the landslide debris, and I have one simple response - look past it. That’s right. With enough effort and determination, you can actually dig past all the munched up BS to the original crystal-bearing rock. The bedrock is so rich, in fact, that I believe it to be on-par if not beyond the richness of the best commercial quartz crystal deposits in Washington.
How you create that link to bedrock is up to you. If you want to move the least amount of dirt and want to discourage people from working your spot, dig a deep winding tunnel. Or if you want to be safe and make it easy-to-work, dig a pit. The bedrock can vary in depth in the soil from just 2 feet (as can be seen in the historic Garden Slug rock face) all the way to some rumors of 40+ feet! If you start finding more and more crystals in the dirt, that’s always a good sign though.
I think a lot of the confusion around Hansen stems from how rich the deposit is. If pockets were more spread-out, then it would be much easier to track float up to a pocket. However, with the jumble sourced from dozens, if not hundreds of individual pockets, it’s virtually impossible to use the age-old tracking technique.
Now you’re at the bedrock, you’ve done most of the work. Locate a quartz seam in the rock and start following it! Usually you’ll have at least a small pocket before the end of the day. Most of the pockets tend to not exceed 8-12” or so - but from there they get much, much bigger. Once you’re past the little leagues, which are usually just a widening of one stringer vein or maybe the junction of two tiny veins, you’ll get much larger pockets. At the junctions of 3 or more veins, or the junctions of thicker 4-6” veins, you’ll find your big pockets. And I mean BIG. Starting from a modest 2 FEET of crystal gravel, the pockets have ranged all the way from a 7-foot man-eating monster a friend and I uncovered in 2020.
Congrats! You’re finding crystals. Here’s a list of the minerals and their occurence to the best of my knowledge.
Actinolite occurs as groups green, golden, or steel-gray hairs included inside quartz crystals. Some crystals are densely included.
Ankerite/Dolomite? occurs as small rhombs altered to limonite clay. They have not been found loose, but some pockets produce crystals that are pitted with thousands of small rhomb imprints. Sometimes the oxidized crystals can be seen as inclusions within quartz scepters. Especially interesting are what are locally deemed “revealed” scepters - where the carbonate overgrows two or three of the m-faces on a quartz crystal and a scepter forms only over the exposed quartz. After the carbonate rots away, the pitted stem of the scepter is visible. There have been no traces of the original mineral found, so this is just a guess. However this is NOT siderite - as I have uncovered several scepters with inclusions of both the mystery carbonate and siderite blades.
Chlorite occurs as green flakes or mossy areas included inside quartz crystals, sometimes forming very attractive phantoms. Some crystals can be very densely included. In some areas, notably the Garden Slug, much of the rock is chloritized to the point where it takes on a green hue.
Epidote occurs as partial radial sprays of dark green crystals. Epidote can be distinguished from actinolite by the radial nature of the sprays and the relatively thick individual crystals (around 0.5mm for epidote versus 0.1-0.2mm for actinolite).
Pyrite occurs as crystals, lightly to completely altered to limonite. The predominant form are cubes, but in certain zones the crystals display an octahedral leaning. Larger crystals are often striated and/or curved. Small pyrite crystals can also be found included in quartz - though usually fractures in the crystals will oxidize them.
Quartz occurs as well-formed terminated crystals from micro (<1cm) all the way to 12cm+. Nearly all crystals are smaller than 6cm. Most crystals are lightly frosty, but some can be glassy. The crystals range from milky white to gem-clear. Scepters, frequently with a light to medium amethyst coloration, are found in the upper reaches of most larger pockets. The amethyst can display good color zoning and is also frequently included with small red and black hematite hairs. The quartz is often broken and recrystallized, many “floater” plates with no points of attachment can be recovered from pockets, some of which feature quite stubby crystals. Japan-law twins to 8cm and rare Dauphiné twins showing x-faces can be found, the latter of which only occurs in the gemmy, glassy crystals. A select few of Japan-law twins show amethyst sceptering.
Siderite occurs as bladed crystals completely altered to limonite. The bladed crystals are not dissimilar from the ones from various Middle Fork locales such as Condor or Pedro. They can range up to 3-4cm in diameter and can form attractive groups with quartz crystals. Sometimes oxidized siderite is partially to completely included inside scepters.
