leucocratic


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Related to leucocratic: Leucocratic Rock

leucocratic

[¦lü·kə¦krad·ik]
(petrology)
Light-colored as applied to igneous rock containing 0-50% dark-colored minerals.
References in periodicals archive ?
The second phase of injection time is close to the main phase and is represented by medium- and fine-grained leucocratic granites with rare potassium feldspar phenocrysts.
The clinopyroxene-bearing albitite is a leucocratic granoblastic, fine- to medium-grained rock, dominated by albite ([Ab.sub.94-96]) and quartz, with minor amounts of clinopyroxene ([En.sub.30-36] [Fs.sub.12-23]; Na = 0.12-0.15 a.p.f.u.; Mg# = 0.57-0.75); (Figure 4(f)).
The granite is leucocratic, shows colour variation and at places is a mixture of yellow, brown and black.
Whole-rock and mineral [sup.40]K/[sup.40]Ar ages have been carried out on mafic and leucocratic sills.
These minerals were collected from miarolitic pegmatites, hydrothermal veins and greisens associated with the upper portions and first-crystallized parts of the peraluminous Mount Antero Granite, especially within the leucocratic variant of the granite.
Spectacular outcrops of such bodies can be seen from the sea on the coastal cliffs of the mountains north of San Pablo, where the leucocratic material, chiefly in thick tabular bodies, accounts for about 20 to 30% of the outcrops.
The granites in this area are leucocratic in appearance and vary in color and mineralogical composition.
Anil points out that "Webster's 2nd defines pilandite as 'a leucocratic porphyry with phenocrysts, a groundmass of anorthoclase, and a little amphibole" and adds "Well at least I know what 'a', 'with', 'of', 'and', and 'little' mean." I checked the definition and it concludes with "Cf.
The main rock types in this borehole are biotite gneisses and sillimanite-biotite gneisses to metatexites (stromatitic migmatites) with relatively rare intercalations of diatexites (leucocratic migmatites).
Also of great interest are newly discovered jadeite deposits in the Polar Urals (Levy Kechpel, etc.), represented by veins in the leucocratic gabbroid mass.
The Karunjhar Hill granite is gray, partly fresh and leucocratic, coarse grained.