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A gabbro composed principally of calcic plagioclase and olivine. Also known as forellenstein.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



an igneous rock of the gabbro group, consisting mainly of basic plagioclase (labradorite or bytownite) and small amounts of olivine. Pyroxenes are either present in negligible amounts or completely absent. Serpentinization of the olivine is sometimes accompanied by the formation of characteristic fissures, which radiate from the olivine grains, in the plagioclase.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Dighem airborne geophysical data suggests that the main mineralised troctolite body continues west of grid line 0 + 00 for approximately an additional 5 km.
So far, we have yet to observe well-developed layering in drilled sequences of oceanic gabbros, and at Site 735 we found evolved gabbros interdigitated with primitive olivine gabbros and troctolites. Detailed chemical mapping of contacts between iron-titanium oxide gabbros and olivine gabbros at Site 735B indicates that evolved melts are sometimes mobilized in response to crustal deformation, and that melt flow may be either diffused through intergranular networks or focused along centimeter-scale channels.
Occurrences of major mafic-ultramafic bodies in the northern Dashwoods Subzone # (a) Location Lithology Mineralogy (b) 1 Puddle Pond Troctolite, ol-gabbro, Varying amounts of gabbro, hbl gabbro, Ol+Pl+Cpx+Hbl+Opx+/-Bt# ol-norite 2 John's Brook Gabbro, hbl-gabbro Cpx+Pl+Hbl# Lake gabbro 3 Whaleback Lherzolite, dunite, Relic Ol+Cpx+opx; Pond websterite, wehrlite, Tr+Chl+Srp+Car; Hbl+Pl# metagabbro 4 W of Silver Dunite, wehrlite, Relic O1+Cpx+Opx+Cr; Pond harzburgite, Tr+Chl+Srp+Car; Am+Chl pyroxenite, gabbro.
Stephen est constitue d'un noyau de dunite et de troctolite, entoure de strates de gabbro et de gabbro a olivine.
Stephen Pluton is divided into four units: dunite, troctolite, olivine gabbro, and gabbro (Fig.
With decreasing cumulus olivine and increasing cumulus plagioclase, the dunite grades into troctolite (Fig.
Stephen Gabbro consists of complexly intermingled olivine gabbro, olivine gabbronorite, and olivine norite, with less abundant gabbro, gabbronorite, norite, troctolite, anorthosite, and dunite.
That all Titanic headstone and Hanson quarry samples are common gabbros, as opposed to, say, troctolites or norites or anorthosites, is essential but not particularly useful in making the case for a match.
Also widespread in Labrador are the anorthosites, granites, diorites and troctolites of the older and probably unrelated 1.35-1.29 Ga Nain plutonic suite (Ryan and James, 2004 and references therein).
Laurentia) COMMENT: The anorthosites, diorites, granites, and troctolites of the 1.35-1.29 Ga Nain Plutonic Suite [e.g.
Magmatic sulphide mineralization is ubiquitous near the basal contacts of most PLI intrusions, and is invariably associated with distinctive, contaminated, sulphide-bearing mafic rocks that include textural equivalents of the 'basal breccias' and 'leopard troctolites' described from Voisey's Bay.