Operation that consists of separating heavier minerals such as gold and sulphides from lighter metals in stream sediment, loose soil or crushed rock in a container shaped like a frying pan. In arid countries a similar operation, winnowing, can be performed without water.

 

The association and order of formation of minerals in a specimen or deposit.

 

A mineral which derives from another mineral, but having the same chemical composition.

 

Like cleavage, parting is a structural break parallel to a possible face with the primary differences being that parting is not found in every mineral specimen and parting can not always be replicated at the atomic level. The majority of partings are incomplete or sealed fracture lines.

 

A luster description showing a glimmering sheen as in the surface of a pearl.

 

A coarsely crystalline area in an igneous formation. Many gem minerals form in pegmatites.

 

A twinned crystal where one crystal has intergrown with another. Have an irregular composition surface separating two individual crystals. Defined by a twin center or twin axis.

 

A cubic-shaped plastic box with a black base, used for mounting thumbnail specimens.

 

Phacops is a genus of trilobites found as fossils in Silurian and Devonian rocks (between 345,000,000 and 430,000,000 years old) in Europe and North America. Phacops is a common and easily recognizable form, with its rounded rather than angular outline, globose head region, and large compound eyes.

 

A crystal which shows an internal image of a crystal, caused by color zoning or inclusions. Crystals that stop growing for awhile and then resume growth produce phantoms when minute mineral crystals that grew on the surface of the crystal during the dormant period are gradually enveloped and trapped inside. The phantom has the shape of the crystal when it stopped growing.

 

Minerals containing the phosphate (PO₄) radical as a major component.

 

A lingering emission of light following exposure to Ultraviolet light or other energy.

 

An area left to support the overlying strata in a mine; sometimes left permanently to support surface structures.

 

The systematic removal of the coal pillars between rooms or chambers to regulate the subsidence of the roof. Also termed "bridging back" the pillar, "drawing" the pillar, or "pulling" the pillar.

 

A crystal face parallel to two crystal axes (three in the hexagonal system).

 

Roof bolting.

 

Like a cluster of rounded grains, about the size of a pea.

 

A mineral found in stream beds, among the gravel and sand.

 

A theory supported by a wide range of evidence that considers the earth's crust and upper mantle to be composed of several large, thin, relatively rigid plates that move relative to one another. Slip on faults that define the plate boundaries commonly results in earthquakes. Several styles of faults bound the plates, including thrust faults along which plate material is subducted or consumed in the mantle, oceanic spreading ridges along which new crustal material is produced, and transform faults that accommodate horizontal slip (strike slip) between adjoining plates.

 

Thin flattened crystals that are plate like.

 

Showing different colors when a crystal is viewed from different directions.

 

A feather-like habit.

 

The change that takes place between crystal structures of the same chemical compound.

 

In mineralogy it means that a single chemical composition can exist with two or more different crystal structures.

 

A type of polymorphism wherein different polymorphs exist in different domains of the same crystal. It has to do with the way that individual layers are stacked within a crystal structure. Polytypism has little geologic consequence.

 

The structure surrounding the immediate entrance to a mine; the mouth of an adit or tunnel.

 

The main roof above the immediate top. Its thickness may vary from a few to several thousand feet.

 

A package or cartridge of explosive which is designed specifically to transmit detonation to other explosives and which does not contain a detonator.

 

A crystal face intersecting lateral axes, and parallel to the vertical axis.

 

An elongated crystal form in which the prism faces are prominent, as in the typical quartz crystal.

 

In the broad sense, prospecting refers to exploration. In the strict sense, prospecting describes the search for surface mineralized showings (by prospectors).

 

A crystal that appears to be one mineral but is actually another. This happens when one crystal retains the original outward shape of another after transforming it internally by replacing the mineral's chemistry with its own chemistry.

 

A crystal face intersecting three crystal axes.

 

A crystal primarily showing the pointed ends, but little or no prism faces.

 

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