Siderite


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Related to Siderite: pyrite

siderite

(sĭd`ərīt) or

chalybite

(kăl`ĭbīt), a mineral, varying in color from brown, green, or gray to black and occurring in nature in massive and crystalline form. A carbonate of iron, FeCO3, it serves as an iron ore, especially in the British Isles. It is widely distributed, being found also in the United States, Europe, South America, and Australia.

Siderite

 

(also spathic iron, chalybite), a mineral, a carbonate of iron with the composition Fe[CO3]. Siderite contains 62.01 percent FeO and 37.99 percent CO2. Its composition often includes isomorphic admixtures of Mn and Mg, which replace iron; more rarely, Ca is present, as are Co and Zn. Siderite cystallizes in the trigonal system, forming rhombohedral, tabular, prismatic, or scalenohedral crystals; the last occur rarely. The mineral usually occurs as granular aggregates, sinters, concretions, spherulites, and earthy agglomerates; it forms deposits in the form of veins, strata, and irregularly shaped bodies. Siderite is yellowish white, gray or greenish gray and turns brown upon weathering. It has a hardness of 4.5 on Mohs’ scale and a density of 3,960 kg/m3.

Depending on the conditions of formation, siderite is classified as being of hydrothermal, sedimentary (infiltration and precipitation), or metamorphosed origin. During weathering and oxidation, siderite is usually converted into hydrogoethite or hydrohematite. Siderite is one of the most important minerals in iron ore.


Siderite

 

any of the iron class of meteorites, according to modern classification. Formerly, the designation “siderite” was applied to iron meteorites that consist almost wholly of nickel-iron.

siderite

[′sid·ə‚rīt]
(mineralogy)
FeCO3 A brownish, gray, or greenish rhombohedral mineral composed of ferrous carbonate; hardness is 4 on Mohs scale, and specific gravity is 3.9. Also known as chalybite; iron spar; rhombohedral iron ore; siderose; sparry iron; spathic iron; white iron ore.
References in periodicals archive ?
Siderite within the Barnsdall Formation of northeastern Oklahoma occurs in four varieties: (1) large nodules lacking a distinct central nucleus, concentrated in horizons bearing articulated crinoids; (2) small concretions with distinct skeletal nuclei consisting of infaunal bivalves and inarticulate brachiopods occurring in horizons relatively lacking in articulated crinoids and crinoid material; (3) large sideritized burrows occurring above crinoid horizons; and (4) concretions nucleated around former sites of soft tissue in large crinoids and productid brachiopods.
For example, Lake O' the Pines (Figure 5) is near the northern Weches in which siderite formed and pyrite is rare.
Both layers contain chlorite, and siliceous and/or siderite nodules.
Finally, certain minerals found predominantly in altered areas, including halloysite, siderite and alunite, [3, 17], have been used to identify subsurface reservoirs.
The dominant constituents of the veins are galena (PbS) and sphalerites (ZnS) in gangue of siderite (FeC[O.
The predominant gangue mineral in ore shoots is manganiferous siderite.
Siderite nodules (sphaerosiderites) in paleosols of the Lower Tuscaloosa Formation of southwestern Mississippi have oxygen isotopic values that are a proxy record for low-latitude precipitation oxygen isotopic values during the mid-Cretaceous greenhouse warming.
The carbonate minerals siderite and rhodochrosite were also commonly detected in partially oxidised peat and in ferricretes.
Other scientists investigating the anomalous buildup of an iron carbonate mineral called siderite also fingered versatile bacteria as the cause.
A siderite vein splay into the footwall of the main South Vein shear appears within the central zone on all three test elevations.