A pseudomorph with the same composition as the original crystal, caused by
a phase transformation; e.g., calcite with aragonite morphology.
CF:pseudomorph
a. The alteration of one mineral into another without change of
composition, such as augite into hornblende in uralitization. Fay
b. With metamorphism, it describes such thorough changes in a rock that
its old components are destroyed and new ones are built up.
See also:allomorphism
Large flint nodule. See also:potstone
An orthorhombic mineral, NiAs2 ; loellingite group; trimorphous
with rammelsbergite and krutovite; metallic tin-white; commonly massive.
A monoclinic mineral, AsS ; trimorphous with realgar and alpha-AsS;
powdery; bright yellow to orange-brown; easily mistaken for orpiment.
A schist derived from a sedimentary rock. See also:orthoschist; schist.
An orthorhombic mineral, UO3 .(2-x)H2 O ; bright yellow; a
dehydration product of schoepite. Formerly called schoepite III.
See also:schoepite
A monoclinic mineral, Fe2+3 (AsO4 )2 .8H
2 O ; vivianite group; dimorphous with symplesite and isomorphous
with koettigite; bluish green.
A trigonal mineral, Cu2 (OH)3 Cl ; forms twinned
rhombohedra; massive or powdery; green to green-black; a secondary mineral
in copper deposits.
A tetragonal mineral, TeO2 ; rutile group; soft; waxy; gray-white;
dimorphous with tellurite; at Cananea, Mexico.
Having planes of cleavage inclined to the axis; also, abounding with
facets of cleavage. Standard, 2
A mobilized portion of an autochthonous granite that has moved higher in
the crust or, more usually, into tectonic domains of lower pressure. It
shows variable marginal relations, in some places migmatitic in others
characterized by a thermal aureole. Schieferdecker
A triclinic mineral, FeAl2(PO4 )2(OH)2.8H2O ; colorless;
forms small prismatic crystals; at Llallagua, Bolivia.
See:messelite
A monoclinic mineral, NaCa2 (Mg,Fe)4 Al(Si6 Al (sub
2) )O22 (OH)2 ; amphibole group; prismatic cleavage; occurs
in dolomitic marbles and in skarns.
One of the most famous of ancient statuary marbles; from the island of
Paros, Greece.
A trigonal mineral, 6[(Ce,La,Nd)2 CaCO3 )3 F2
] ; vitreous to resinous; forms acute hexagonal bipyramids; in veins, such
as the emerald deposits of Columbia; also in alkalic pegmatites. Named for
J.J. Paris.
A monoclinic mineral, Ni3 (Bi,Pb)2 S2 ; metallic;
bronze; has three cleavages; in a magmatic sulfide deposit, Insizwa, South
Africa.
Treatment of steel in hot aqueous solution of free phosphoric acid and
manganese dihydrogen phosphate, other salts sometimes being used as
accelerators. A fine-grained insoluble film of ferric phosphate is formed
in a few minutes, which is corrosion resistant. Pryor, 3
A method for producing low-temperature coke in which each retort is a
monobloc iron casting 9 ft (2.7 m) high, containing 12 tubes, which taper
from 4-1/2 in (11.4 cm) at the top to 5-1/4 in (13.3 cm) at the bottom. A
battery contains 36 retorts in 2 rows of 18. Retorts and combustion
chambers are arranged alternately, so that each retort is located in a
radiation chamber formed by the walls of adjacent combustion chambers. The
retorts are heated only by radiation from these walls, so that there is no
overheating and the inside temperature of the retorts can be maintained
accurately at 1,112 degrees F (600 degrees C). A cooling chamber is fitted
below each pair of retorts, of a size sufficient to hold the coke from
both. The pairs of retorts are charged and discharged every 4 h.
Syn:Coalite process
A process used to recover precious metals from lead. It is based on the
principle that if 1% to 2% of zinc is stirred into molten lead, a compound
of zinc with gold and silver separates out and can be skimmed off.
ASM, 1