jaw crusher
A machine for reducing the size of materials by impact or crushing between a fixed plate and an oscillating plate, or between two oscillating plates, forming a tapered jaw.

molybdenite
A hexagonal and trigonal mineral, MoS₂ ; polymorphous with jordisite; foliated; soft; metallic lead gray; an accessory in granites and deep veins; an ore of molybdenum.

ore
The naturally occurring material from which a mineral or minerals of economic value can be extracted profitably or to satisfy social or political objectives. The term is generally but not always used to refer to metalliferous material, and is often modified by the names of the valuable constituent; e.g., iron ore.

pyrite
An isometric mineral, FeS₂ ; dimorphous with marcasite; forms a series with cattierite; crystallizes in cubes and pyritohedra; sparks readily if struck by steel; metallic; pale bronze to brass yellow; hardness varies from 6.0 to 6.5; occurs in veins, as magmatic segregation, as accessory in igneous rocks, and in metamorphic rocks; a source of sulfur. Also known as fool's gold.

quartz
a. A trigonal mineral, SiO₂
b. Any hard, gold or silver ore, as distinguished from gravel or earth. Hence, quartz mining, as distinguished from hydraulic mining, etc.

raise
A vertical or inclined opening in a mine driven upward from a level to connect with the level above, or to explore the ground for a limited distance above one level. After two levels are connected, the connection may be a winze or a raise, depending upon which level is taken as the point of reference.

rod mill
A mill for fine grinding, somewhat similar to a ball mill, but employing long steel rods instead of balls to effect the grinding.

scheelite
A tetragonal mineral, CaWO₄ , with molybdenum replacing tungsten toward powellite CaMoO₄ ; prismatic cleavage; specific gravity, 5.9 to 6.1; varicolored, fluoresces bright blue; in limestone and pneumatolitic veins near granite contacts, granite pegmatites; a source of tungsten.

schist
A strongly foliated crystalline rock, formed by dynamic metamorphism, that can be readily split into thin flakes or slabs due to the well developed parallelism of more than 50% of the minerals present, particularly those of lamellar or elongate prismatic habit, e.g., mica and hornblende. The mineral composition is not an essential factor in its definition unless specif. included in the rock name, e.g., quartz-muscovite schist. Varieties may also be based on general composition, e.g., calc-silicate schist, amphibole schist; or on texture, e.g., spotted schist.

shaft
A vertical or nearly vertical opening of a mine.

sphalerite
An isometric mineral, ZnS , with Zn replaced by Fe with minor Mn, As, and Cd; trimorphous with wurtzite and matraite; perfect dodecahedral cleavage; resinous to adamantine; occurs with galena in veins and irregular replacement in limestone; a source of zinc. Also known as: zinc blende, jack, blackjack, steel jack, false galena, pseudogalena, mock ore, mock lead.

stamp mill
An apparatus, and the building containing it, in which rock is crushed by descending pestles (stamps), operated by water power or steam power. Amalgamation is usually combined with crushing when gold or silver is the metal sought, but copper, tin, and other ores are stamped to prepare them for dressing. The technique is obsolete.

stope
Any excavation in a mine, other than development workings, made for the purpose of extracting ore. The outlines of the orebody determine the outlines of the stope.

vein
A rock fissure filled by intruded mineral matter. Many valuable minerals are codeposited with gangue stuff in veins. Usually the formation is steep to vertical, unlike a bedded deposit in which values are sandwiched horizontally. Vein is typically long, deep, and relatively narrow.