adit: A nearly horizontal entrance to a hard-rock mine.
argonaut: The men who came to California during the Gold Rush (after the Argonauts of Greek mythology who sailed on the ship Argo in search of riches).
arrastra: An apparatus used to grind ore by means of a heavy stone that is dragged around in a circle, normally by mules or oxen.
assay: To determine the value of a sample of ore, in ounces per ton, by testing using a chemical evaluation.
bonanza: To miners, a body of rich ore.
charcoal kiln (or oven): A structure into which wood is placed and subjected to intense heat through a controlled, slow burning. Charcoal is a longer-lasting, more efficient fuel than wood and is often used to power mills and smelters. If the kiln is used to convert coal to coke, it’s called a “coke oven.”
chloride: Usually refers to ores containing chloride of silver.
claim: A tract of land with defined boundaries that includes mineral rights extending downward from the surface.
claim-jumping (or jumping a claim): Illegally taking over someone else’s claim.
diggings (or diggins): Evidence of mining efforts, such as placer, hydraulic, or dredge workings.
dredge: An apparatus, usually on a flat-bottomed boat, that scoops material out of a river to extract gold-bearing sand or gravel; used in “dredging” or “dredge mining.”
dust: Minute gold particles found in placer deposits.
flotation: A method of mineral separation in a mill in which water, in combination with chemicals, “floats” finely crushed minerals of value to separate them from the detritus, which sinks. Process used in a flotation mill.
flume: An inclined, manmade channel, usually of wood, used to convey water or mine waste, often for long distances.
gallows frame: See “headframe,” below.
giant: The nozzle on the end of a pipe through which water is forced in hydraulic mining. Also called a “monitor.”
grubstake: An advance of money, food, and/or supplies to a prospector in return for a share of any discoveries.
hard-rock mining: The process in which a primary deposit is mined by removing ore-bearing rock by tunneling into the earth. Also known as quartz mining, since gold is frequently found in quartz deposits.
headframe: The vertical apparatus over a mine shaft that has cables to be lowered down the shaft for raising either ore or a cage; sometimes called a “gallows frame.”
high-grade ore: Rich ore.
high-grading: The theft of rich ore, usually by a miner working for someone else who owns the mine.
hopper: In mining, a structure with funnels from which the contents, loaded from above, can be emptied for purposes of transportation.
horn silver: Silver chloride, a native ore of silver. Also known as Cerargyrite.
hydraulic mining: A method of mining using powerful jets of water to wash away a bank of gold-bearing earth. Also known by miners as “hydraulicking.”
ingot: A cast bar or block of a metal.
lode: A continuous mineral-bearing deposit or vein (see also “Mother Lode”). In Nevada, the famous lode was the Comstock Lode of Virginia City.
mill: A building in which rock is crushed to extract minerals by one of several methods. If this is done by stamps (heavy hammers or pestles), it is a stamp mill. If by iron balls, it is a ball mill. The mill is usually constructed on the side of a hill to utilize its slope—hence, a “gravity-fed mill.”
mining district: An area of land described (usually for legal purposes) and designated as containing valuable minerals in paying amounts.
monitor: See “giant.”
Mother Lode: The principal lode passing through a district or section of the country; from the same term in Spanish, La Veta Madre. In California, it refers specifically to the hundred-mile-long concentration of gold on the western slopes of the Sierra Nevada.
mucker: A person or machine that clears material such as rock in a mine.
nugget: A lump of native gold or other mineral. The largest found in California’s Mother Lode weighed 195 pounds.
ore: A mineral of sufficient concentration, quantity, and value to be mined at a profit.
ore sorter: A structure, usually near a mine, in which higher-grade ore is sorted from lower-grade ore or waste before being sent to the mill or smelter.
pan: To look for placer gold by washing earth, gravel, or sand, usually in a streambed, by using a shallow, concave dish—a “pan.”
placer: A waterborne deposit of sand or gravel containing heavier materials such as gold, which have been eroded from their original bedrock and concentrated as small particles that can be washed, or “panned,” out (see also “secondary deposit”).
pocket: In primary deposits, a small but rich concentration of gold embedded in quartz. In secondary deposits, a hole or indentation in a stream bed in which gold dust or nuggets have been trapped.
powderhouse: A structure placed safely away from a mine that stores such volatile materials as gunpowder or dynamite. The building’s walls are usually very stout, but its roof is intentionally of flimsier construction, so if the contents should explode, the main force of the blast would be into the air.
primary deposit: A deposit of gold or other mineral found in its original location. Ore is extracted by hard-rock mining or hydraulic mining.
prospect: Mineral workings of unproven value.
prospector: He who searches for prospects.
quartz mining: See “hard-rock mining.”
rocker: A portable sluicebox used by prospectors.
salting: To place valuable minerals in a place in which they do not actually occur. Done to deceive. Therefore, a salted claim is one that is intended to lure the unsuspecting investor into a scam.
secondary deposit: A deposit of gold or other mineral that has moved from its original location by water. Ore is extracted by placer mining or dredging.
shaft: A vertical or nearly vertical opening into the earth for hard-rock mining.
slag: The waste product of a smelter; hence, “slag dumps.”
sluicebox: A wooden trough in which placer deposits are sluiced, or “washed,” to retrieve gold from the deposits.
smelter: A building or complex in which material is melted in order to separate impurities from pure metal.
square set: A set of timbers that are cut so that they form a ninety-degree angle and so that they can be combined with other “sets” to create a framework that safely buttresses a mine. First used in the Comstock Lode.
strike: The discovery of a primary or secondary deposit of gold or other mineral in sufficient concentration and/or quantity to be mined profitably.
tailings: Waste or refuse left after milling is complete; sometimes used more generally, although incorrectly, to indicate waste dumps. Because of improved technology, older tailings have often been reworked to extract minerals that were left behind from an older, cruder milling process.
tramway: An apparatus for moving materials such as ore, rock, or even supplies in buckets suspended from pulleys that run on a cable.
tunnel: A horizontal or nearly horizontal underground passage open at one end at least.
vein: A zone or belt of valuable mineral within less valuable neighboring rock.
waste dump: Waste rock, not of sufficient value to warrant milling, that comes out of the mine; usually found immediately outside the mine entrance.
workings: A general term indicating any mining development; when that development is exhausted, it is “worked out.”