Goldmanite
Encyclopedia
Goldmanite is a green or greenish-brown silicate mineral of the garnet
group with a chemical formula of Ca3(V3+,Al,Fe3+)2(SiO4)3.
and is named after Marcus Isaac Goldman (1881–1965), an American petrologist
. The type locality
, South Laguna (or Sandy) mine area, was in vanadium rich clay
within a metamorphosed
uranium
-vanadium deposit in sandstone
. While studying these deposits, it was noted that garnet in relatively unmineralized sandstone is colorless, whereas garnet in dark well-mineralized rock, containing abundant vanadium clay and uranium deposits was deep green or brownish green. To confirm the green color was due to vanadium, two samples of garnet were separated from dark ore, analyzed, and found to be rich in vanadium. The South Laguna mine area was studied in 1955 and 1956 as part of an investigation of the geology and uranium deposits of the Laguna district by the USGS.
; in drill core from the North Sea
; from Klatovy
, Czech Republic
; Ishimskaya Luka, northern Kazakhstan
; the Slyudyanka complex, Sayan Mountains, near Lake Baikal
region of Russia
and the Yamoto mine, Kagoshima Prefecture
, Japan
. It is also found in the metalliferious black shales of the Korean Peninsula.
was found by immersion to be 1.821±.001, using sodium light and adjusting for small temperature changes. Like so many calcium garnets, goldmanite was found to be weakly anisotropic. The cell edge of goldmanite is 12.011 Å
, as determined by x-ray powder diffraction analysis.
Garnet
The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name "garnet" may come from either the Middle English word gernet meaning 'dark red', or the Latin granatus , possibly a reference to the Punica granatum , a plant with red seeds...
group with a chemical formula of Ca3(V3+,Al,Fe3+)2(SiO4)3.
Discovery
It was first described in 1964 for an occurrence in the Laguna District, Cibola County, New MexicoNew Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
and is named after Marcus Isaac Goldman (1881–1965), an American petrologist
Petrology
Petrology is the branch of geology that studies rocks, and the conditions in which rocks form....
. The type locality
Type locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
, South Laguna (or Sandy) mine area, was in vanadium rich clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
within a metamorphosed
Metamorphism
Metamorphism is the solid-state recrystallization of pre-existing rocks due to changes in physical and chemical conditions, primarily heat, pressure, and the introduction of chemically active fluids. Mineralogical, chemical and crystallographic changes can occur during this process...
uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
-vanadium deposit in sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
. While studying these deposits, it was noted that garnet in relatively unmineralized sandstone is colorless, whereas garnet in dark well-mineralized rock, containing abundant vanadium clay and uranium deposits was deep green or brownish green. To confirm the green color was due to vanadium, two samples of garnet were separated from dark ore, analyzed, and found to be rich in vanadium. The South Laguna mine area was studied in 1955 and 1956 as part of an investigation of the geology and uranium deposits of the Laguna district by the USGS.
Occurrence
In addition to the type location in the Sandy mine in New Mexico, it has been reported from Coat-an-Noz, Cotes-du-Nord, FranceFrance
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
; in drill core from the North Sea
North Sea
In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...
; from Klatovy
Klatovy
Klatovy is a town in the Plzeň Region of the Czech Republic.Klatovy is also the seat of the Municipality with Extended Competence and Municipality with Commissioned Local Authority.- History :Klatovy was founded during 1260–1263 by Přemysl Otakar II....
, Czech Republic
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
; Ishimskaya Luka, northern Kazakhstan
Kazakhstan
Kazakhstan , officially the Republic of Kazakhstan, is a transcontinental country in Central Asia and Eastern Europe. Ranked as the ninth largest country in the world, it is also the world's largest landlocked country; its territory of is greater than Western Europe...
; the Slyudyanka complex, Sayan Mountains, near Lake Baikal
Lake Baikal
Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...
region of Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
and the Yamoto mine, Kagoshima Prefecture
Kagoshima Prefecture
is a prefecture of Japan located on the island of Kyushu. The capital is the city of Kagoshima.- Geography :Kagoshima Prefecture is located at the southwest tip of Kyushu and includes a chain of islands stretching further to the southwest for a few hundred kilometers...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It is also found in the metalliferious black shales of the Korean Peninsula.
Composition
Goldmanite is composed of calcium (24.79%), aluminium (3.34%), vanadium (12.6%), iron (2.3%), silicon (17.37%), and oxygen (39.59%). Its chemical formula is Ca3(V3+,Al,Fe3+)2(SiO4)3.Properties
The approximate density (3.74±.03) of goldmanite was determined by finding the density of diluted Clerici solution in which small fragments remained suspended. Because of fine grain size, more accurate determination of density was not attempted. The calculated density (3.737) agrees with the approximate value. The index of refractionRefractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
was found by immersion to be 1.821±.001, using sodium light and adjusting for small temperature changes. Like so many calcium garnets, goldmanite was found to be weakly anisotropic. The cell edge of goldmanite is 12.011 Å
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
, as determined by x-ray powder diffraction analysis.