A tetragonal mineral, ferric oxyhydroxide beta-FeO(OH,Cl) ; rust colored;
occurs in soils.
A hexagonal mineral (epsilon-MnO2 ), trimorphous with pyrolusite
and ramsdellite. See:pyrolusite
Used for separating fine-size solids from coarser solids in a wet pulp;
consists of an interrupted-flight screw conveyor operating in an inclined
trough.
A monoclinic mineral, Mn4 Mg(AsO4 )2 .4H2 O ;
forms reddish-brown rounded aggregates.
An orthorhombic mineral, MgB6 O7 (OH)6 .2H2 O.
An isometric mineral, manganese sulfide, MnS ; iron-black; in epithermal
vein deposits; an ore of manganese. Formerly called alabandine.
Syn:manganblende; manganese glance.
A massive form of gypsum; very fine grained; commonly snow-white and
translucent but may be delicately shaded or tinted with light-colored
tones. Because of its softness, it can be easily carved and polished.
Widely used for ornamental purposes. Chemically it is CaSO4 .2H
2 O . It is a beautifully banded form of stalagmitic calcite
occurring in Algeria and in Egypt. Syn:oriental alabaster; onyx marble.
CMD
Impure ozokerite containing an admixture of country rocks and found in the
region of the Caspian Sea. Tomkeieff
A monoclinic mineral, PbSiO3 . Syn:lead silicate;
lead metasilicate.
In the United States, a commonly used term for a granitic rock containing
few, if any, dark minerals. The term is used to designate granitoid rocks
in which quartz constitutes 20% to 60% of the felsic minerals and in which
the ratio of alkali feldspar to total feldspar is greater than 90%; i.e.,
the equivalent of alkali granite. Alaskite is a commercial source of
feldspar near Spruce Pine, NC. CF:aplogranite
A dark brown to black asphaltic pyrobitumen with conchoidal fracture
occurring as veins 1 to 16 ft (0.3 to 4.9 m) wide in the Albert Shale of
Albert County, NB, Can. It is partly soluble in turpentine, but
practically insoluble in alcohol. It was earlier called albert coal.
AGI
An early name for albertite. Tomkeieff
a. A triclinic mineral, NaAlSi3 O8 ; feldspar group, with up
to 10 mol % CaAl replacing NaSi; a member of the plagioclase and the
alkali feldspar series; prismatic cleavage; a common rock-forming mineral
in granite, intermediate to felsic igneous rocks, low-temperature
metamorphic rocks, and hydrothermal cavities and veins; can be used as a
glaze in ceramics.
b. The pure sodium-feldspar end member in the plagioclase series.
Syn:sodium feldspar; white feldspar; white schorl.
albite-epidote-amphibolite facies
The set of metamorphic mineral assemblages (facies) in which basic rocks
are represented by hornblende + albite + epidote. Equivalent to Eskola's
epidote-amphibolite facies, it is of uncertain status, transitional
between the greenschist facies and the amphibolite facies. It is generally
believed to be favored by the higher pressures of regional metamorphism.
AGI
See:albitite
A porphyritic igneous rock, containing phenocrysts of albite in a
groundmass chiefly consisting of albite. Muscovite, garnet, apatite,
quartz, and opaque oxides are common accessory minerals.
Syn:albitophyre; albite porphyrite. AGI
Introduction of, or replacement by, albite, usually replacing a more
calcic plagioclase. AGI
See:albitite
A kaolinitic clay found in Dorsetshire, England. It is used as a
low-percentage addition to natural molding sands. Osborne
The immature chemistry of the Middle Ages, characterized by the pursuit of
the transmutation of base metals into gold, and the search for the
alkahest and the panacea. Standard, 2
C2 H5 OH ; made from grain. Not to be confused with methyl
hydroxide or methanol. Syn:ethanol