Solid rock underlying gold-bearing gravel.
Black sands are the good news/bad news of placer mining. You will
probably never pan gold that does not have some black sands swirling
around in the bottom of the pan. You will often pan black sands with no
gold in them.
Mining ground held under federal or state laws by virtue of location and record.
Using screens or other methods to separate material in smaller and smaller categories in order to aid in the retrieval of gold. The thought being that even while heavy and very small piece of gold can get lost or displaced by a rock many, or several hundreds of times larger than itself.
Generally meaning some amount of visible gold, most often in a pan while prospecting.
A shallow excavation dug in the ground for mineral exploration or extraction. Often at the base of a basalt flow.
Sand or other fine-sized material associated with placer deposits. Usually the last material left during the panning process.
Finest gold dust, much of which will float.
FeS2 – iron pyrite,or often mica, sometimes mistaken for gold.
Placer Mining Terms
Uses the same pump/hose combo as a dredge, but has a hopper on top with
bars so big rocks roll off, then a sluice at the bottom for the
concentrates to separate. Uses miner’s moss or carpeting. High bankers work in two ways: you can either shovel dirt into the top of the high banker, or you can use the suction dredge to squirt the gravels into the top hopper.
Trommels are large cylinders with holes inside that spin and wash with
water. Raw pay dirt goes in one end, and cleaned gravels and rocks come
out the other. Concentrates are trapped and stored in large quantities.
Some trommels have many layers of screening in the cylinder. Trommels
work great with backhoes and large volumes of water.
This is the practice of squirting high-pressure water jets at entire
hillsides, washing all the dirt away, down to bedrock. The water flow is
directed toward sluice boxes to wash the gold from the gravel.
Hydraulicking is blamed for filling the Sacramento River with sediment
and creating a massive ecological disaster out of much of the area. It
is not legal.
In some areas where flooding is common, the large river boulders take on
a green “skin” of moss. This moss traps black sands and gold particles
much like “miner’s moss” in high-efficiency sluices. By crushing the
moss and releasing the dirt and sand, you can find a lot of flour gold
The desert is a harsh environment for gold prospectors. Without lots of
water, miners have to bring their own in, and hoard it for cleanup. One
way to make concentrates out in the desert is with a dry washer, which
vibrates and uses the fluid characteristics of air to trap heavy
particles from pay dirt.
George “Buzzard” Massie, founder of the Gold Prospectors Association of
America (GPAA) discussed on one of his shows a cheap, easy to build
contraption invented by a man named Henry Henry. Another name is a “poop
chute”. The Henry Henry is a two or three foot length of ribbed, three-
inch irrigation pipe. Cut the pipe in half and nail it to a two-by-four.
Tilt it up at a good angle; you’ll have to test it out. You should have
a mini sluice now. Use a hose, or set up some buckets, to get a trickle
of gold going through the Henry Henry. Use a teaspoon and feed in your
black sands. The gold in the sands should sit in the first couple of
Shaker tables vibrate out the lighter minerals and catch the heavy gold
in tiny traps in the table. The black sands run off the end. These
tables are very efficient, and very expensive.
Some people swear by their spiral pans, usually the ones driven by an
motor – not the ones you spin by yourself. As with anything else, your
mileage may vary, but the concept is pretty straightforward: you dump
in concentrates and run the motor. The gold is picked up in the spiral
and moved to the center, where it collects into a cup.
More General Terms and Lode Mining Terms
ADIT — An entrance to a mine, generally a horizontal tunnel.
AMALGAMATION — The technique of using mercury to attract small particles of crushed gold and join with them in an amalgam, or alloy. Gold may be recovered by distilling off the mercury.
ARRASTRA — A mill, consisting of one or more large stones dragged around on a circular bed, used to grind ore.
CHILEAN MILL — A machine, somewhat like the arrastra, in which heavy stone wheels turn about a central shaft and crush ore.
CORNISH PUMP — A type of pump developed in Cornwall, England, and commonly used in deep mines of the nineteenth century to raise underground water.
CROSSCUT — A horizontal tunnel driven perpendicular to the main direction of a vein.
DRIFT — An underground tunnel which follows the course of a vein.
FOOTWALL — The wall or rock on the underside of a stope.
GALLERY — A drift which has been enlarged into an underground room by the extraction of ore.
GANGUE — The worthless rock in a vein which holds valuable metals.
GEOLOGY — The science or study of rocks in the earth.
HANGING WALL — The wall or rock on the upper or topside of an ore deposit.
KIBBLE — Iron Cornish bucket used to hoist ore and miners to the surface.
LEVEL — Horizontal passageways or tunnels in the mine leading from shafts, established at regular intervals.
LODE — An ore deposit occurring in place within definite boundaries separating it from the adjoining rocks.
METAMORPHISM — A pronounced change in the constitution of rock effected by pressure, heat, and water that results in a more compact and more highly crystalline condition.
MINERAL — A substance which may, or may not, be of economic value, that occurs naturally in the earth. It is homogenous, has certain chemical makeup and usually appears in crystal or grain form.
ORE — A mixture of minerals and gangue from which at least one of the minerals can be extracted at a profit.
PAN — A shallow metal dish used for washing earth and stones to separate the gold.
PLACER — An alluvial or glacial deposit containing particles of gold or other valuable minerals.
RETORT — A vessel in which substances are distilled or decomposed by heat.
ROCKER — A device for washing gold-bearing earth to recover the precious metal.
SHAFT — A vertical entrance to a mine cut downward from the surface.
SQUARE SET — A set of timbers used for support in underground mining.
STAMP MILL — A machine for crushing ore by the weight of constantly falling pieces of iron, stone, or wood. The action
approximates the pulverizing of material with a mortar and pestle.
STOPE — An excavation created by the removal of ore and consequent widening of the drift.
TAILINGS — Finely ground particles of ore deposited as waste after processing by a mill or smelter.
VEIN — An opening, fissure, or crack in rock, containing mineralized material.
WASTE — Rock containing no ore but removed in the course of mining operations.
WHIM — A winding machine used for hoisting ore out of a shaft.
WINDLASS — A device, smaller than a whim, used to raise ore from a shaft.
WINZE — A vertical or inclined opening sunk from a point inside a mine.