GLOSSARY - Archaeological Chemistry - page 479

electrolyte A solution in water of any substance that undergoes ionization , dissoci-
ating into positively and negatively charged ions .
electrolytic cell The assembly of two electrodes - a positive anode and a negative
cathode - between which there is an electrolyte in which electrolysis may take place.
electromagnetic radiation (EMR) A form of energy such as visible light , infrared ,
ultraviolet , X , and gamma rays , that moves at the speed of light; all forms of EMR
are originated by the interaction of electrical and magnetic energy; see periodic
process .
electron A subatomic particle that bears the smallest electric charge known.
electron capture A radioactive decay process in which an electron is captured by, and
merges with an atomic nucleus ; the electron combines with a proton to form a
neutron that stays within the nucleus. The mass number of the resulting isotope
is unchanged, but its atomic number is decreased by one.
electron microprobe See microprobe , electron .
electron microscope See microscope , electron .
electron spin resonance (ESR) dating See dating, electron spin resonance .
electrum (1) A naturally occurring alloy of gold and silver usually containing over
20% silver; (2) synthetic (human-made) silver-gold alloys varying in composition
from almost pure gold to almost pure silver.
element A substance that consists of only one type of atom and cannot, therefore, be
separated into other substances .
element, major An essential component of a material , also referred to as a main or
matrix element , that determines the nature and properties of the material ; see minor
element , trace element .
element, minor A nonessential element of a component of a material that occurs
within its basic matrix structure in a concentration below 1%; see major element ,
trace element .
element, primordial An element created at the time of the creation of the earth.
element, trace A nonessential component of a material that occurs in very low con-
centration, usually expressed in ppm or ppb .
elemental analysis See analysis , elemental .
elementary particle See particle , elementary .
elutriation A technique for separating smaller and larger particles of finely divided
materials such as clay, by subjecting them to an upward flow of a fluid, such as air
or water; the flowing fluid causes different sized particles to settle at different rates
and therefore to separate.
emerald A green, precious gemstone that consists mainly of metal silicates .
emery A dark brown variety of the mineral corundum .
emission spectrum See spectrum , emission .

empirical formula See formula , empirical .

EMR Acronym for electromagnetic radiation .