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native mercury

See:quicksilver

native nickel-iron

See:awaruite; josephinite.

native water

See:formation water

natrite

A monoclinic mineral, NaCO3 ; occurs in very soluble, white,
granular masses; a rare mineral in the alkalic complexes of the Kola
peninsula, Russia.

natrium

See:sodium

natrochalcite

A monoclinic mineral, NaCu2 (SO4 )2 (OH).H2 O;
bright emerald-green; forms steep pyramidal crystals; a secondary copper
mineral at Chuquicamata, Chile.

natrojarosite

A trigonal mineral, NaFe3+3 (SO4 )2 (OH)
6 ; alunite group; in earthy masses and minute scales; a common
alteration product in pyrite-bearing deposits. Formerly called utahite.

natrolite

An orthorhombic mineral, Na16 [Al16 Si24 O80].16H2 O;
zeolite group, which may contain appreciable calcium;
dimorphous with tetranatrolite; forms acicular to slender prismatic
crystals in cavities and veins, esp. in mafic and alkaline igneous rocks.
Syn:laubanite

natromontebrasite

A triclinic mineral, (Na,Li)Al(PO4 )(OH,F) ; amblygonite group; in
granitic pegmatites associated with other lithium minerals. Formerly
called fremontite.

natron

A monoclinic mineral, Na2 CO3 .10H2 O ; very soluble;
forms earthy or granular crusts and efflorescences; in nonmarine
evaporites and on lavas.

natrona

See:sodium sesquicarbonate

natron granite

Granite abormally high in soda, presumably from the presence of a
soda-rich orthoclase or of anorthoclase. It is also called soda granite.

nattle

Eng. To make a slight rattling or tapping noise. Said of a mine when
movement or settling is taking place. Webster 3rd; Fay

natural air crossing

An air crossing in which two airways are separated by rock in its natural
state. BS, 8

natural asphalt

Asphalt before crushing or refining, as mined or quarried in the case of
natural rock asphalt, or surface-excavated in the case of lake deposits.
Hammond

natural carbon

Carbon found in a shape that has not been artificially modified. Also
called natural stone. Long

natural cement

A hydraulic cement produced by pulverizing and then heating naturally
occurring rock (cement rock) containing appropriate proportions of
limestone, clay, magnesia, and iron. Ignition temperatures are usually
lower than for portland cement. Final pulverizing is necessary as with
portland cement.

natural coke

Coke made by natural processes, usually by the intrusion of an igneous
dike. See also:cinder coal; clinker; coke coal; cokeite. Hess

natural convection

See:convection

natural diamond

This abrasive is the densest form of crystallized carbon, the hardest
substance known. It occurs most commonly as well-developed crystals in
volcanic pipes or in alluvial deposits. Bort (boart or borts) sometimes
refers to all diamonds not suitable for gems, or it may refer to
off-color, flawed, or impure diamonds not fit for use for gems or most
other industrial applications, but suitable for the preparation of diamond
grain and powder for use in lapping or the manufacture of most diamond
grinding wheels. This type of bort is also called crushing bort or
fragmented bort. ACSG, 2

natural Earth current

Electric current in the Earth not due to human activity.
Schieferdecker