Robertsite
Encyclopedia
Robertsite, Ca34[(OH)3| (PO4)2]2·3(H2O) (alternatively formulated Ca2(Mn3(PO4)3O2)(H2O)3), is a secondary phosphate mineral named for Willard Lincoln Roberts (1923–1987), mineralogist and professor at South Dakota School of Mines in Rapid City, South Dakota
.
The type locality for Robertsite is the Tip Top mine, Custer County, South Dakota
, USA. Robertsite occurs at the Tip Top Mine as minute crystal aggregates
and crusts found on quartz
associated with triphylite. It is a dark reddish brown to black monoclinic mineral.
It occurs as a secondary mineral in pegmatite
. It is also reported from the Khoa Rang Kai phosphate deposit, Chiang Mai
, Thailand
in a limestone
guano
deposit. It is associated with rockbridgeite, ferrisicklerite, leucophosphite, jahnsite, montgomeryite, collinsite and hureaulite
in the type locality. In the guano deposit it occurs with carbonate-fluorapatite
, calcite
, dolomite
, quartz
and clay minerals. In the Omo Valley of Ethiopia
it occurs with mitridatite associated with fossil
fish in Pliocene
/Pleistocene
lake
sediments.
Recently, in an exploration conducted by the Italian La Venta Geographical Association, confirmed the existence of Robertsite in the Puerto Princesa Subterranean River National Park
, located about 50 kilometres (31 mi) north of the city center of Puerto Princesa, Palawan
, Philippines
.
Rapid City, South Dakota
Rapid City is the second-largest city in the U.S. state of South Dakota, and the county seat of Pennington County. Named after Rapid Creek on which the city is established, it is set against the eastern slope of the Black Hills mountain range. The population was 67,956 as of the 2010 Census. Rapid...
.
The type locality for Robertsite is the Tip Top mine, Custer County, South Dakota
Custer County, South Dakota
As of the census of 2000, there were 7,275 people, 2,970 households, and 2,067 families residing in the county. The population density was 5 people per square mile . There were 3,624 housing units at an average density of 2 per square mile...
, USA. Robertsite occurs at the Tip Top Mine as minute crystal aggregates
Aggregate (composite)
Aggregate is the component of a composite material that resists compressive stress and provides bulk to the composite material. For efficient filling, aggregate should be much smaller than the finished item, but have a wide variety of sizes...
and crusts found on quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
associated with triphylite. It is a dark reddish brown to black monoclinic mineral.
It occurs as a secondary mineral in pegmatite
Pegmatite
A pegmatite is a very crystalline, intrusive igneous rock composed of interlocking crystals usually larger than 2.5 cm in size; such rocks are referred to as pegmatitic....
. It is also reported from the Khoa Rang Kai phosphate deposit, Chiang Mai
Chiang Mai
Chiang Mai sometimes written as "Chiengmai" or "Chiangmai", is the largest and most culturally significant city in northern Thailand. It is the capital of Chiang Mai Province , a former capital of the Kingdom of Lanna and was the tributary Kingdom of Chiang Mai from 1774 until 1939. It is...
, Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
in a limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
guano
Guano
Guano is the excrement of seabirds, cave dwelling bats, and seals. Guano manure is an effective fertilizer due to its high levels of phosphorus and nitrogen and also its lack of odor. It was an important source of nitrates for gunpowder...
deposit. It is associated with rockbridgeite, ferrisicklerite, leucophosphite, jahnsite, montgomeryite, collinsite and hureaulite
Hureaulite
Hureaulite is a manganese phosphate with the formula Mn2+522·4H2O. It was discovered in 1825 and named in 1826 for the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France...
in the type locality. In the guano deposit it occurs with carbonate-fluorapatite
Fluorapatite
Fluorapatite, often with the alternate spelling of fluoroapatite, is a mineral with the formula Ca53F . Fluorapatite is a hard crystalline solid. Although samples can have various color , the pure mineral is colorless as expected for a material lacking transition metals...
, calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
, quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
and clay minerals. In the Omo Valley of Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
it occurs with mitridatite associated with fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
fish in Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
/Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
lake
Lacustrine
Lacustrine means "of a lake" or "relating to a lake".Specifically, it may refer to:*Lacustrine plain*Lacustrine delta-Fish:*Lacustrine goby , a type of small fish found in Philippine waters belonging to the Gobiidae family, known in Tagalog as dulong-See also:*Fluvial - of or relating a...
sediments.
Recently, in an exploration conducted by the Italian La Venta Geographical Association, confirmed the existence of Robertsite in the Puerto Princesa Subterranean River National Park
Puerto Princesa Subterranean River National Park
The Puerto Princesa Subterranean River National Park is located about north of the city centre of Puerto Princesa, Palawan, Philippines. The river also called Puerto Princesa Underground River. The national park is located in the Saint Paul Mountain Range on the northern coast of the island. It is...
, located about 50 kilometres (31 mi) north of the city center of Puerto Princesa, Palawan
Palawan
Palawan is an island province of the Philippines located in the MIMAROPA region or Region 4. Its capital is Puerto Princesa City, and it is the largest province in the country in terms of total area of jurisdiction. The islands of Palawan stretch from Mindoro in the northeast to Borneo in the...
, Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
.
- Mitridatite group:
- ArseniosideriteArseniosideriteArseniosiderite is a rare arsenate mineral formed by the oxidation of other arsenic-containing minerals, such as scorodite or arsenopyrite. It occurs in association with beudantite, carminite, dussertite, pharmacolite, pitticite, adamite and erythrite. The name arseniosiderite reflects two major...
-mitridatite series:- Ca2(Fe3+)3[(O)2|(AsO4)3]·3H2O
- to
- Ca2(Fe3+)3[(O)2|(PO4)3]·3H2O
- Arseniosiderite-robertsite series:
- Ca2(Fe3+)3[(O)2|(AsO4)3]·3H2O
- to
- Ca3(Mn3+)4[(OH)3|(PO4)2]2·3H2O
- Arseniosiderite