Chambersite
Encyclopedia
Chambersite is a manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

 borate mineral
Borate mineral
The borate minerals are minerals which contain a borate anion group. The borate units may be polymerised similar to the SiO4 unit of the silicate mineral class. This results in B2O5, B3O6, B2O4 anions as well as more complex structures which include hydroxide or halogen anions...

 with formula:Mn3B7O13Cl. It is a member of the borate mineral series that includes other minerals such as ericacite, Fe3B7O13Cl, and boracite
Boracite
Boracite is a magnesium borate mineral with formula: Mg3B7O13Cl. It occurs as blue green, colorless, gray, yellow to white crystals in the orthorhombic - pyramidal crystal system. Boracite also shows pseudo-isometric cubical and octahedral forms. These are thought to be the result of transition...

 Mg3B7O13Cl. When chambersite was first discovered, it was the second chemical analogue of boracite to be found in nature. It was discovered as a mineral at Barber's Hill salt dome
Salt dome
A salt dome is a type of structural dome formed when a thick bed of evaporite minerals found at depth intrudes vertically into surrounding rock strata, forming a diapir....

 in Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

 in 1957 and in 1971 at the Dongshuichang deposit in Jixian
Ji County, Tianjin
Ji County is a county in the far north of Tianjin municipality, China of cultural and historical significance . The administration of the county was transferred from Hebei province to Tianjin in 1973...

, Tianjin
Tianjin
' is a metropolis in northern China and one of the five national central cities of the People's Republic of China. It is governed as a direct-controlled municipality, one of four such designations, and is, thus, under direct administration of the central government...

, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

. Chambersite occurs associated with the evaporite
Evaporite
Evaporite is a name for a water-soluble mineral sediment that result from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporate deposits, marine which can also be described as ocean deposits, and non-marine which are found in standing bodies of...

 minerals halite
Halite
Halite , commonly known as rock salt, is the mineral form of sodium chloride . Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on the amount and type of impurities...

, anhydrite
Anhydrite
Anhydrite is a mineral – anhydrous calcium sulfate, CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium and strontium sulfates, as might be expected from the...

, and gypsum
Gypsum
Gypsum is a very soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is found in alabaster, a decorative stone used in Ancient Egypt. It is the second softest mineral on the Mohs Hardness Scale...

.

Chemical and physical properties

When chambersite was first discovered in Barber's Hill, the dominate form was the positive tetrahedron
Tetrahedron
In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...

, but single morphological twinned crystal was found with interpenetrating tetrahedrons with the twinning axis. The ore discovered in China had formed in high grades that are spindle and granular that form micritic aggregates because the boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...

 present is very pure and in low grades that had formed spheroids that are radially oriented. When chambersite in China was compared it had the same chemical oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....

 ratio as the samples found in Barber's Hill.
Table 1. Chemical composition of chambersite in oxide percent
MnO 41.87
FeO 1.28
MgO 0.05
CaO tr
B2O3 49.5
Cl 6.34
Total % 99.04

Geologic occurrence

Chambersite minerals were first found in 1957 in brine
Brine
Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...

 returns from a gas storage well in the Barber's Hill salt dome and the age of the dome is not definitely known, but it is at least Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 and probably upper Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to  Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...

. Other chambersite deposits with this similar geologic occurrence can be found in the area of the Gulf Coast of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. The Venice dome in Plaquemines Parish, Louisiana
Plaquemines Parish, Louisiana
Plaquemines Parish is the parish with the most combined land and water area in the U.S. state of Louisiana. The parish seat is Pointe à la Hache...

 is a site that has a shallow piercement salt dome, LPG storage and brine production. Other chambersite deposits can be found in the Penobsquis deposit in Southern New Brunswick
New Brunswick
New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...

, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

, which has high grade salt deposits as well as a significant borate mineral concentration, including chambersite. Other chambersite deposits can be found as ores in Ji County, Tianjin
Ji County, Tianjin
Ji County is a county in the far north of Tianjin municipality, China of cultural and historical significance . The administration of the county was transferred from Hebei province to Tianjin in 1973...

, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...

, an area that is considered to have had much magnetic activity and submarine volcanism
Volcanism
Volcanism is the phenomenon connected with volcanoes and volcanic activity. It includes all phenomena resulting from and causing magma within the crust or mantle of a planet to rise through the crust and form volcanic rocks on the surface....

 in a subtidal lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...

.

Special characteristics

Chambersite was named after the county where it was first discovered, Chambers County, Texas, USA. Optical examination and x-ray powder diffraction indicated the mineral to be related to boracite but different from any other published description.
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