According to reports Keno Hill was like attending an elite graduate school for a geologist because of the difficulty in finding small but rich deposits using surface exploration techniques, and following them underground.
There are 65 different minerals found in the Keno Hill mining region. 4 of the main ones found are Hawleyite, siderite, silver and sphalerite.
They are pictured below:
As you wander over the hill you will see large piles of what looks like loose shale. These are called tailings. They are the leftovers of the placer style mining that took place through the years at Keno.
Geologists looking for various minerals do so in several ways. They wander about and pick up interesting rocks, as do many tourists. They use a technique called systematic surface exploration.Sometimes they initially use a bulldozer and shear off the first few inches of rock to see what lies just beneath the surface. They often drill and take core samples.
'Camp' is a geological term that is used to describe a cluster of deposits and occurrences that have a similar mineralogy and geological setting. The Keno Hill Camp is defined as a belt approximately 21 km long and 2 to 6.5 km wide that crosses parts of Galena, Keno and Sourdough Hills. It extends from the Silver King mine (#2) at the west end, to the Caribou Hill mine (#37) at the east end. The camp was named Keno Hill because the earliest large-scale mining took place there, even though most of the silver was actually produced from mines situated on Galena Hill. The camp contains 16 'important' deposits, defined as those that produced over 15.55 t (500,000 oz) of Ag, another 19 that shipped smaller amounts to a smelter, and 35 minor occurrences.
"The region is located within the western part of the Selwyn Basin. The stratigraphy consists of deformed and metamorphosed basinal sediments that accumulated at the edge of the Neoproterozoic to Paleozoic continental margin. During the Jurassic to Cretaceous periods (160 to 130 Ma), these rocks were subjected to compressional orogenesis related to large-scale plate convergence. This shortening episode also caused ductile, north-south directed thrusting, which generated three main thrust panels containing highly strained to transposed basin strata. In the Mayo-McQuesten district, the panels are separated by the Robert Service and Tombstone thrust faults.
Between 90 and 95 million years ago (Ma), a tectonic change from convergent-oblique to subduction-dextral strike-slip movement resulted in an episode of magmatism and the emplacement of the Tombstone series of intermediate to felsic plutons. About 65 Ma, renewed compressional tectonics that formed the Mackenzie Mountains induced another magmatic event and the emplacement of the McQuesten series of intrusions."
The layered succession has been metamorphosed to the green-schist facies. It was historically simply divided into three informal units known as the Lower Schist, Central Quartzite, and Upper Schist.
The Lower Schist Unit consists of graphitic, calcareous and sericitic schist horizons, thin-bedded quartzite, and minor thick-bedded quartzite. In addition, sills and/or boudin of metadiorite and metagabbro (greenstone) up to 1 km long and 30 m thick are common, mostly on Keno Hill. The greenstone bodies form outcrops but the layered rocks weather recessively. When schist is exposed to surface weathering, it generally disintegrates quickly into small silica-rich fragments in a clay matrix.
The Central Quartzite Unit is approximately 700-m thick and consists primarily of bedded and massive quartzite and lesser thin schist and phyllite layers. This unit is the most important host to mineralization. Tight isoclinal folding has been exposed in underground workings and the walls of open-pits. Greenstone horizons are most common in the lower half of the unit. Although the quartzite would be expected to form prominent outcrops, they are actually rare. The thick-bedded and massive members are fractured and frost-heaved into large slabs of felsenmeer that raft downhill for considerable distances and locally override the Lower Schist Unit. A frozen field of these slabs blanketed by an insulating vegetation layer created a formidable barrier to prospecting and bedrock exploration.
The Upper Schist Unit consists of quartz-mica schist, quartzite, graphitic schist and minor limestone; it also weathers recessively. Rhyolite (quartz-feldspar porphyry) sills, conformable with schistosity, have intruded the Lower and Upper Schist units and perhaps the Central Quartzite Unit, as well. The largest sill is at least 40 m thick and has been traced across Galena Hill from west of the Silver King mine to Duncan Creek.
Keno Hill mineralization has been classified as part of a distinct family of vein deposits "silver-lead-zinc veins in clastic metasedimentary terranes" by Beaudoin and Sangster (1992).
The principal Ag mineral is tetrahedrite (called 'grey copper' by prospectors), which is ubiquitous throughout the camp. Another less important Ag mineral is pyrargyrite (called 'ruby silver' by prospectors), which was only abundant in the Silver King, Husky, Elsa and, particularly, the Lucky Queen mines.
Keno Hill sphalerite is a Fe-rich variety called 'marmatite', which is dark brown to black and known to prospectors as 'blackjack'.
Hawleyite (CdS),a new, rare cadmium mineral, was first recognized by Boyle (1965). It forms bright yellow, earthy coatings on sphalerite, pyrite and siderite in the oxidation zone.
Pleistocene ice, which occurs in most veins within the permafrost zone, was first studied in the Lucky Queen mine (Wernecke 1932). Two types are present, a clear variety with tiny air bubbles and a milky type intergrown with ice crystals.
Native silver is an unusual component of the ice, occurring as needles, leaves, wires and flake-like crystals at the Lucky Queen, Elsa and Keno mines. It is thought to be of secondary origin, with silver growth occurring at the same time as the ice crystals. In 1990, geologist Bill Wengzynowski discovered a specimen of leaf silver at the Lucky Queen mine and was able to deliver it, still frozen in ice, to the Canadian Museum of Nature in Ottawa.
While we were visiting this location, we met a Cat operator who told us that he had just uncovered two large veins of silver for the current mining company. Look carefully and you may find a rock or two of one of the most common minerals.
The History
Silver mining began on Keno Hill, previously called Sheep Hill, in 1919 when Louis Bouvette discovered silver in July. Today the village of Keno has a population of approximately 20 people. The 10.5 kilometre drive to the signpost monument takes you to a very scenic, panoramic view of the valley and mountain ranges.
To log this cache answer the following questions using the information from above or online and email the answers to us.
1. What type of ore did Louis Beauvette find?
2. Name the two types of material the ore comes in contact with to form silver.
3.Identify one of the obvious rock types in the pile at the sign.
4. Please take a photograph of yourself/or your Gpsr at this site with one of the types of rock.
Post a note and wait for our affirmative reply to log as found. We will try to be quick.
For more information regarding mining at Keno Hill see geological reports on http://www.thefreelibrary.com/Great+mining+camps+of+Canada+1.+The+history+and+geology+of+the+Keno...-a0156291083