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methyl acetone

A mixture of methyl acetate and acetone. Used as a solvent.
Crispin

methylene iodide

A heavy liquid used for mineral separation (sp gr, 3.33); also for
refractive index determination (R.I.=1.74). CF:Clerici solution;
Sonstadt solution; Klein solution; bromoform.

metore

Both capping and gossan. AGI

metra

A pocket implement combining the uses of many instruments, such as
thermometer, level, plummet, and lens. Standard, 2

metric carat

An international unit equal to 200 mg that had been adopted in most
European countries and in Japan when it was made the standard in the
United States in 1913. Abbrev.: M.C. and cm. See also:carat
Webster 3rd

Mexican diamond

Rock crystal (quartz).

Mexican onyx

Yellowish brown or greenish brown banded calcite. See also:onyx marble;
Gibraltar stone.

Mexican turquoise

Turquoise from the central part of Baja California, Mexico.

Mexican water opal

A fire opal from Mexico.

meyerhofferite

A triclinic mineral, Ca2 B6 O6 (OH)10 .2H (sub
2) O ; forms prismatic, commonly tabular, crystals or is fibrous; an
alteration product of inyoite from Inyo County, CA.

meymacite

An amorphous mineral, WO3 .2H2 O ; resinous; yellow brown.

miargyrite

A monoclinic mineral, AgSbS2 ; soft; metallic; in low-temperature
hydrothermal veins; an ore of silver.

miarolite

A granite having miarolitic cavities; a textural modification of normal
granite. Johannsen

miarolithite

A chorismite having miarolitic cavities or remnants thereof; a variety of
ophthalmite. AGI

miarolitic

A term applied to small irregular cavities in igneous rocks, esp.
granites, into which small crystals of the rock-forming minerals protrude;
characteristic of, pertaining to, or occurring in such cavities. Also,
said of a rock containing such cavities. CF:drusy

miarolitic cavity

A cavity of irregular shape in certain plutonic rocks. Crystals of the
rock constituents sometimes project into the cavity. CF:druse; vug.
Schieferdecker

miascite

A mixture of strontianite and calcite. Hey, 1

mica

a. A group of phyllosilicate minerals having the general composition, X
2 Y4-6 Z8 O20 (OH,F) where X=(Ba,Ca,Cs,H (sub
3) O,K,Na,NH4 ), Y=(Al,Cr,Fe,Li,Mg,Mn,V,Zn), and Z=(Al,Be,Fe,Si);
may be monoclinic, pseudohexagonal or pseudo-orthorhombic; soft; perfect
basal (micaceous) cleavage yielding tough, elastic flakes and sheets;
colorless, white, yellow, green, brown, or black; excellent electrical and
thermal insulators (isinglass); common rock-forming minerals in igneous,
metamorphic, and sedimentary rocks. See also:brittle mica
Syn:glimmer; isinglass.
b. The mineral group anandite, annite, biotite, bityite, celadonite,
chernykhite, clintonite, ephesite, ferri-annite, glauconite, hendricksite,
kinoshitalite, lepidolite, margarite, masutomilite, montdorite, muscovite,
nanpingite, norrishite, paragonite, phlogopite, polylithionite,
preiswerkite, roscoelite, siderophyllite, sodium phlogopite, taeniolite,
tobelite, wonesite, and zinnwaldite.

micaceous

a. Consisting of or containing mica; e.g., a micaceous sediment.
b. Resembling mica; i.e., thinly foliated.

micaceous iron ore

Hematite in which the texture is foliated or micaceous; some micaceous
varieties are soft and unctuous. Rice, 1

micaceous sandstone

A sandstone containing conspicuous layers or flakes of mica, usually
muscovite. Syn:metaxite