Arfvedsonite, Aegirine (Narssârssuk, Greenland);
Natrolite, Benitoite, Joaquinite-(Ce) (San Benito County,
California, USA); Nordite-(La), Lomonosovite, Sodalite,
Ussingite (Kola Peninsula, Russia).
a rare lithium titanium silicate mineral that is popular
as mineral specimens but rarely available as faceted
gems. Neptunite forms shiney black, elongated,
prismatic crystals which are usually square in cross
section with pointed terminations. It is opaque and
black except in very small fragments.
Thin fragments may be dark, blood red to dark, brownish
red. Neptunite is usually
available only as beautiful mineral specimens set
in a matrix of pure white Natrolite
along with blue Benitoite
crystals and rarely with orangish brown Jaoquinite-(Ce) crystals. Although
there are several locations throughout the world to
find Neptunite crystals, the most well known source of Neptunite is at
the now closed Benitoite
Gem Mine, San Benito County, California, USA.
is one of the unusual minerals that exhibit the piezoelectric
effect. Piezoelectricity is the ability of some
mineral crystals to generate a voltage in response to applied mechanical
stress such as an external pressure. Piezoelectricity was discovered in 1880 by French physicists, brothers Jacques and Pierre Curie.
was named in 1893 by Swedish mineralogist Gustav Flink
(1848-1931) for Neptune, the Roman god of the sea. This name
was given because of Neptunite's close association
at its type locality at Narssârssuk,
Greenland with the mineral Aegirine,
named for Ægir, god of the sea and king of all
sea creatures in Norse mythology. Aegirine was named
in 1834 by Norwegian priest and mineralogist Hans Morten Thrane Esmark
distribution: from Narssârssuk, Iglunguak, and
the Ilímaussaq intrusion, Greenland. In the Inagli
massif, 30 km west of Aldan, Yakutia, and in the Khibiny
and Lovozero massifs, Kola Peninsula, Russia. From the
Khan-Bogdinskii granitic massif, Gobi, Mongolia. In
the Dara-i-Pioz massif, Alai Range, Tien Shan, Tajikistan.
From Barnavave, near Carlingford, County Louth, Ireland.
At Mont Saint-Hilaire, Quebec, and Seal Lake, Labrador,
Newfoundland, Canada. In the USA, splendid crystals
from the Benitoite Gem mine and Mina Numero Uno, San
Benito County, California, and at Point of Rocks, Colfax
County, New Mexico. From near Woodsreef, New South Wales,