a. Dolomite with calcium and magnesium disordered within layers rather
than ordered by layer.
b. An imperfectly crystallized synthetic material of composition near
CaMg(CO3 )2 .
See:protogine
Said of original rocks as opposed to derived rocks, and including saline
deposits, coal, igneous rocks, and ore deposits. The term is no longer
used. Holmes, 2
A granitic rock, occurring in the Alps, that has gneissic structure,
contains sericite, chlorite, epidote, and garnet, and shows evidence of a
composite origin or of crystallization (or partial recrystallization)
under stress after consolidation. Also spelled protogene. The term, dating
from 1806, is obsolete. AGI
a. A mylonitic rock produced from contact-metamorphosed rock, with
granulation and flowage being due to overthrusts following the contact
surfaces between intrusion and country rock. AGI
b. A coherent crush breccia whose characteristically lenticular,
megascopic particles faintly retain primary structures. It is a lower
grade in the development of mylonite and ultramylonite.
CF:ultramylonite
An elementary particle with a single positive electrical charge and a mass
approx. 1,847 times that of an electron. The atomic number of an atom
equals the number of protons in its nucleus. Lyman
A well-sorted, quartz-enriched sandstone that lacks the well-rounded
grains of an orthoquartzite; specif. a lithic sandstone intermediate in
composition between subgraywacke and orthoquartzite. AGI
In older writings, any primary mineralized material too low in tenor to
constitute ore but from which ore may be formed through secondary
enrichment. As commonly employed today, the rock below the sulfide zone of
supergene enrichment; the primary material that cannot be produced at a
profit under existing conditions but that may become profitable with
technological advances or price increases. See also:oxidized zone;
sulfide zone.
An instrument used in drawing and plotting, designed for laying out or
measuring angles on a flat or curved surface, and consisting of a plate
marked with units of circular measure. See also:goniometer
A trigonal mineral, Ag3 AsS3 ; dimorphous with xanthoconite;
rhombohedral cleavage; soft; ruby red; occurs in low-temperature or
secondary-enrichment veins; a minor source of silver.
Syn:light ruby silver; light red silver ore.
a. To determine, by boring from the surface or driving a passageway
underground, the location and character of a coalbed or the nature of rock
strata. Hudson
b. To establish, by drilling, trenching, underground openings, or other
means, that a given deposit of a valuable substance exists, and that its
grade and dimensions equal or exceed some specified amounts.
See also:proved reserve
See:proved reserve
An ore deposit that has been reliably established as to its volume,
tonnage, and quality by approved sampling, valuing, and testing methods
supervised by a suitably qualified person. The proved reserve is the
overridingly important asset of a mine, and by its nature is a wasting one
from the start of exploitation unless it is increased by further
development. Syn:proved ore
A place of origin; specif. the area from which the constituent materials
of a sedimentary rock or facies are derived. Also, the rocks of which this
area is composed. CF:distributive province
AGI
a. To show that the requirements for receiving a patent for government
land have been satisfied. Webster 3rd
b. Can. To establish economic value of a property. Hoffman
a. A borehole drilled for prospecting purposes.
b. Advance bore or heading into a mineral deposit, made either to check
the quality of the ore being approached or to relocate a deposit that has
been distorted or dislocated by faulting. Pryor, 3
A steel ring that has been accurately turned, heat treated, and polished.
It is precisely calibrated in a testing machine by measuring its
deflection for different loads and can be used for measuring applied loads
on a structure. Hammond
The establishment of the quantity and grade of coal or ore available for
working by means of geological surveys, exploratory drilling, or exploring
headings. Nelson
a. The determination of the compounds contained in a mixture as
distinguished from ultimate analysis, which is the determination of the
elements contained in a compound. Used in the analysis of coal.
Standard, 2; Fay
b. The determination, by prescribed methods, of moisture, volatile matter,
fixed carbon (by difference), and ash. The term proximate analysis does
not include determinations of chemical elements or determinations other
than those named. See also:chemical constitution of coal
A Schlumberger log based on the principle of shallow investigation; as its
name implies it is markedly affected by material that lies in its
immediate proximity. It depends for its operation on the forcing of a more
or less horizontal beam of current into the formation. Its vertical
resolution is about 6 in (15 cm) and it is almost impervious to the
presence of a mud cake on the formation wall. Wyllie
The basic legal standard for discovery under the mining law that states:
Where minerals have been found and the evidence is of such a character
that a person of ordinary prudence would be justified in the further
expenditure of his labor and means, with a reasonable prospect of success
in developing a valuable mine, the requirements of the statute have been
met. SME, 1