Lamprophyre


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Related to Lamprophyre: Ijolite

lamprophyre

[′lam·prə‚fī·ər]
(petrology)
Any of a group of igneous rocks characterized by a porphyritic texture in which abundant, large crystals of dark-colored minerals appear set in a not visibly crystalline matrix.

Lamprophyre

 

melanocratic igneous dike rock that differs from the corresponding igneous rocks to which it is genetically related by its sharply increased content of dark minerals (usually at least 30 percent of the rock). The color of lamprophyre varies from dark gray to black. Its constituents include feldspar (sometimes feldspathoid) and dark minerals (biotite, amphibole, pyroxene, and sometimes olivine). In the porphyritic varieties of lamprophyre the phenocrysts are usually represented by dark minerals—this is called lamprophyric texture. There are calcalkalic lamprophyres (spessartite, kersantite) and alkalic lamprophyres (camptonite, alnöite). Lamprophyres sometimes grade into porphyrites.

References in periodicals archive ?
A 1-2 m thick lamprophyre dyke in Beavertail State Park cross-cuts [S.
39]Ar technique and hence to better constrain the age of pre-rifting alkaline magmatism in southeastern New England and establish if it did, indeed, progress from north to south as suggested by other lamprophyre ages from Avalonia (Fig.
Farther north, a swarm of carbonatite and lamprophyre dykes was outlined in the course of mapping the Aigneau Lake area (Fig.
The size of the samples and the lateral distribution of the locations indicate that diamonds in lamprophyres are widespread in the region and that further exploration may yield some positive finds, Calhoun said in a press release.
Initial fracture propagation can occur along a fault (Weinberg 1996), although no offsets are evident relative to the earlier east-trending lamprophyre dykes at the map scale.
Conditions are now good for drilling as the ground is frozen and conditions are the same as the previous successful drill program near Hadishville, when NSDM discovered lamprophyre.
015 Ga: An important intraplate event is the widespread Behm Canal event [#29a] of the Cordillera, which is also known as the Tertiary Lamprophyre Province.
The previous Phase one drill program near Hadashville discovered a lamprophyre.
The pluton is cut by lamprophyre and alkaline olivine diabase dykes of early Jurassic age (Cant et al.
Cabo Mining out of Vancouver has struck an interesting twist in Lorraine Township south of Cobalt with the discovery of diamonds in lamprophyre and associated heterolithic breccias, similar to diamond discoveries made in Wawa, he says.
Phase 1: This resulted in the discovery of a lamprophyre on Shire 1.