Gabronite or Gabbronite is a former name for a mineral found in Norway, no longer widely used. It describes a form of
scapolite or
nepheline
Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites ...
.
Current views
Mindat.org
Mindat.org is a non-commercial online database, claiming to be the largest mineral database and mineralogy, mineralogical reference website on the Internet. It is used by professional mineralogists, geologists, and amateur mineral collecting, mi ...
defines the term "Gabbronite" as:
:Old discredited name, has been referred to as both Scapolite and Nepheline.
lark, 1993, 249 - "Hey's Mineral Index - 3rd Edition" Wiktionary defines "
Gabbronite" as "A compact variety of scapolite, resembling
gabbro."
The term is sometimes used in modern geological descriptions. Thus a description of the
Matamec Ecological Reserve in Quebec, Canada says, "Elsewhere, igneous rock is composed of anorthosite, gabronite and granite."
A web search is likely to show a polished mostly-black stone used in jewelry.
Descriptions
William Phillips (1773–1828) lists the mineral under SILEX, and describes it as follows:
According to
Parker Cleaveland
Parker Cleaveland (January 1, 1780 – August 15, 1858) was an American geologist and mineralogist, born in Rowley, Massachusetts.
He was identified with the early progress of the natural sciences. After having attending the Dummer Academy in B ...
(1780–1858) the mineral is probably a variety of Fettstein.
Cleaveland defines it as follows:
''
Webster's 1828 English Dictionary'' gives:
:GA'BRONITE, n. A mineral, supposed to be a variety of fettstein. It occurs in masses, whose structure is more or less foliated, or sometimes compact. Its colors are gray, bluish or greenish gray, and sometimes red.
Armand Dufrénoy
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(1792–1857) describes the mineral as:
:Gabronite. – This mineral, found only in Arendal in Norway, is found in an amorphous mass, with a compact or hard
lamellar texture... The
École des Mines
École may refer to:
* an elementary school in the French educational stages normally followed by secondary education
Secondary education or post-primary education covers two phases on the International Standard Classification of Education scal ...
possesses a sample in which I have been able to recognize not only that the angles are straight, but that there is a diagonal cleavage at an angle of about 135°; from which it follows that the prism is square, as in wernérite [common
scapolite]: the shine of gabronite is fat and oily. Its color is dirty gray, greenish gray; it barely scratches glass: its specific gravity is 2.74. The composition of gabronite, which I will give in a few lines, departs from that of wernérite by the great quantity of soda it contains. This circumstance induced M. Beudant to associate it with
nepheline
Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites ...
; but the six-sided prism form of this latter species is opposed to this association.
See also
*
Gabbronorite
Notes
Sources
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{{DEFAULTSORT:Gabronite
Gemstones
Silicon compounds