leucocratic


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Related to leucocratic: Leucocratic Rock

leucocratic

(ˌluːkəˈkrætɪk)
adj
(Geological Science) (of igneous rocks) light-coloured because of a low content of ferromagnesian minerals
[C20: from German leukokrat, from leuco- + Greek kratein to rule]
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References in periodicals archive ?
Mapping and prospecting have identified outcropping Nickel Mountain-type leucocratic gabbros at 'K9' (Click here to View Map).
These are biotite-amphibole, biotite granites, granodiorites (Ob, Novosibirsk massifs) and biotite, biotite-muscovite leucocratic granites (Kolyvan, Barlak massifs).
The present study considered samples from igneous and metamorphic rocks and their weathering products in outcrops near the towns of A Coruna (NW Spain) and Braga (NW Portugal), which were based on the available geological mapping (IGME [14, 15]; Ferreira et al., [16]), and our field studies can be described as gabbro (3 samples in A Coruna), leucocratic body in gabbro (1 sample in A Coruna), biotite-rich granites (4 samples in Braga), leucocratic granite (3 samples in A Coruna and 5 samples in Braga), and Silurian siliciclastic metamorphic rocks (7 samples in Braga).
It characteristically takes the form of a medium-grained, granoblastic, light grey, or pink leucocratic rock (Figure 3(h)).
1): Bocabec Gabbro--greyish green, locally layered, medium-grained gabbro and minor associated granitic rocks; Utopia Granite--typically red, leucocratic, medium--to coarse-grained, equigranular, biotite granite; Welsford, Jake Lee Mountain, and Parks Brook granites--beige to pink, mediumgrained and equigranular to fine-grained and porphyritic, amphibole-bearing, peralkaline granites; Magaguadavic Granite--greyish pink, coarse-grained, megacrystic granite; John Lee Brook Granite--light grey, medium-grained, equigranular, garnetiferous, two-mica granite; and Mount Douglas Granite--light pink, medium-to-coarse-grained and equigranular to fine-grained and porphyritic, rapakivitextured, biotite granite.
Some look like the host rocks, except for finer grain size, and many are leucocratic. Perthite, albite, quartz, and sparse microcline are accompanied by small quantities of opaque oxide, with or without biotite, titanite and secondary minerals (Fig.
Pegmatitic and fine-grained leucocratic bodies of variable size are frequent and usually showing sharp contacts with the Main Unit.
The rock exposures occur as highly denuded hills of essentially fine-medium textures with closely spaced alternating bands of leucocratic and melanocratic minerals.
The Kagi Metamorphics are composed of leucocratic felsic chlorite-muscovite -quartz-feldspar schist (low grade greenschist facies), some garnet-mica schist and minor metabasite (Department of Mineral Resources, unpublished).