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E

Effervesce       Forming and breaking gas bubbles by chemical reaction.

Electrical grounding       To connect with the ground to make the earth part of the circuit.

Electrolysis       An electric current is passed through a solution containing dissolved metals, causing the metals to be deposited on to a cathode.

Electrolytic refining       The process of purifying metal ingots that are suspended as anodes in an electrolytic bath, alternated with refined sheets of the same metal which act as starters or cathodes.

Electrostatic separator       Machine employing static electrical charges to separate heavy mineral concentrates.

Electrum       Native gold containing a large amount of alloyed silver.

Element       Substance composed of atoms that cannot be broken down by ordinary chemical means; metals, nonmetals and certain gasses.

Eluvium       Material produced by decomposing rock formations where water movement and abrasion are not present.

EM survey       A geophysical survey method which measures the electromagnetic properties of rocks.

Emulsion       A mixture of water and oily substances.

En echelon       A geological term used to describe the geometric structure of minerals found in a roughly parallel but staggered fashion.

End line       Line across the width of a lode chain.

Entry       Refers to mining location; also opening to underground workings.

Entry       An underground horizontal or near-horizontal passage used for haulage, ventilation, or as a mainway; a coal heading; a working place where the coal is extracted from the seam in the initial mining; same as "gate" and "roadway," both British terms.

Environmental impact study       A written report, compiled prior to a production decision, that examines the effects proposed mining activities will have on the natural surroundings of an exploration property.

Epigenetic       Orebodies formed by hydrothermal fluids and gases that were introduced into the host rocks from elsewhere, filling cavities in the host rock.

Epithermal deposit       A mineral deposit consisting of veins and replacement bodies, usually in volcanic or sedimentary rocks, containing precious metals, or, more rarely, base metals.

Equity financing       The provision of funds by buying shares.

Era       A large division of geologic time - the Precambrian era, for example.

Erosion       The breaking down and subsequent removal of either rock or surface material by wind, rain, wave action, freezing and thawing and other processes.