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Containing magnesium and iron and only a very small amount of silica. Used of igneous rock.


(Geological Science) (of such igneous rocks as peridotite) containing less than 45 per cent silica


(ˌʌl trəˈbeɪ sɪk)

(of rocks) containing iron and magnesium, with little or no silica.
References in periodicals archive ?
Quite common in basic and ultrabasic rocks, Co is a rare metal existing in porphyritic igneous rocks in small quantities (Dixon, 2012).
Petrographic analysis reveals that these rocks are serpentinites, which represent rocks generated by secondary alteration of ultrabasic rocks.
The sources of this anomalous zone consist of amphibolites and ultrabasic complex (serpentinites), which are assigned to the Letovice Crystalline (Salansky and Gnojek, 2002).
Ironstone genesis is usually associated with weathering of Fe-rich basic (Schwertmann 1993; Beauvais 2009) or ultrabasic (Trescases et al.
Physical and Mechanical Properties of Serpentinized Ultrabasic Rocks in NW Turkey.
Geology Rank Weight Total weight Charnockite Group 6 4 24 Gneiss 6 4 24 Ultrabasic rocks 6 3 18 (a) Geology Weight.
This mineral occurs in calc-silicate marbles with no ultrabasic rocks occurring either as enclaves or as discrete bodies in the vicinity.
Eocene flysch facies in the study area, set in the South East of Iran, the zone name Zabul - Baluch, Sistan Suture zone and or zone Nehbandan - Kash is Rock units in the study area includes a colorful melange , flysch of Cretaceous, Paleocene and Eocene flysch of the ultrabasic parts, materials, volcanic and clastic rocks are Neogene [1].
Geologists classify igneous rocks as acid, intermediate, basic or ultrabasic on the basis of their (decreasing) content of silica (Si[O.