Return to index Decembre 7, 2011

Gold, copper and silver discovered in tonalite rocks on 33 CARATS

MONTREAL, QUEBEC, CANADA - For the first time, gold is discovered in rocks on 33 CARATS diamond project of DIOS EXPLORATION, Upper Eastmain River area, Quebec, within targeted tonalitic intrusive rocks :  six samples returned values of gold, silver and copper up to 3.18 g/t, 18 g/t and 1.22%, respectively. See table below for more results.  Detailed geological mapping by DIOS some 5-10 km northwest of the volcanic hosted Eastmain gold deposit helped define a 2 by 6 km tonalitic phase specifically targeted for its gold potential in the western part of a felsic pluton around which is wrapped the Eastmain Greenstone Belt.  The mineralized (1-2% pyrite) sicilified tonalite glacial float samples were collected up-ice of a glacial gold train in till.  Boulders are angular and their size suggest an outcrop source within 2 km, where tonalite was mapped,  and not in the eastern part of the property further away where granodiorite was mapped.

Gold mineralization in tonalite boulders correlates with significant values of copper and silver, and related values in bismuth, an indication of porphyry type deposits.  An anomalous gold bearing outcrop was also discovered, with high exploration potential in the surrounding one km or more radius.  DIOS  considers these results very significant as it indicates that this part of the eastern Eastmain volcanic belt has a potential for a copper-gold porphyry deposit related to the synvolcanic Lac Erasme pluton.  The Otish road towards Renard diamond deposit will go through DIOS’ property, 1-2  kilometres east of the main gold potential area.

Rock sample description

Gold (g/t)

Silver (g/t)

Copper (%)



Sub angular boulder, 2 x 2 x1m, moderately fractured, felsic volcanic, 20-30% mm  QZ porphyric crystals , 2-3% BO, 5-10% rusty QZ veinlets, non-magnetic, 2-3% PY-CPY





Boulder 1.5 x 1.5 x 1 m, medium grain tonalite, QZ(35%) – PG(30%) – BO(35%), 1-2% QZ veins, moderately foliated, strongly magnetic, altered: biotization-silicification, disseminated 2-4% CPY, traces  PY





Boulder 1 x 0.5 x 0.5 m, medium to coarse grain tonalite, QZ(35%) – PG(35%) – BO

(30%), strongly foliated, altered, magnetic, 20-30% mm QZ veins developed in foliation, alteration comprises biotization, hematization and silicification , disseminated 1-3% PY





Angular boulder 4 x 4  x 2 m, medium to coarse grain tonalite containing a 2-3 cm rusty QZ vein , QZ(40%) – PG(40%) – BO(20%), magnetic, disseminated traces PY





Sub angular boulder 1.5 x 1.3 x 1.1m, medium to coarse grain tonalite, QZ(40%) – PG(30%) – BO( 30%), moderately foliated, non-magnetic, alteration comprises BO veinlets, carbonatation and silicification , disseminated 3-5% PY-CPY and patchy MC





Sub angular boulder 4 x 4 x 5 m, medium to coarse grain tonalite, QZ(40%) – PG(30%) – BO( 30%), non-foliated, strongly magnetic, alteration comprises biotization and silicification , disseminated 3-4% PY-CPY





QZ: quartz, BO: biotite, CPY: chalchopyrite,  PY: pyrite, PG: plagioclase feldspar





Siliceous and biotitic alteration affects most samples. Carbonatation is sometimes observed. Mineralization consists of disseminated pyrite, chalchopyrite and malachite within rocks but also in rusty quartz veins. Sulphide content varies between traces and 5%. Mineralization and alteration types combined with the important till gold train suggest a real potential for a large copper-gold porphyry system that could be the source of the goldbearing boulders found during the 2011 campaign.

Gold values above 50 ppb were returned from 13 samples out of 154 sent to analysis, 10 of them were taken in metric sub-angular to angular blocks of felsic intrusive and 12 samples, including one outcrop, are located in the till gold train The highest gold assay returned 3.18 g/t from a volcanic felsic block. Only one anomalous sample comes from an outcrop of tonalite. Three auriferous boulders are found in the vicinity of this outcrop. Six samples returned sub-economic to economic values of gold, silver and copper up to 3.18 g/t, 18 g/t and 1.22% respectively.


A one week prospecting program was completed over a tonalite (granodiorite) plug and adjacent volcanics up-ice of a glacial auriferous train (glacial till gold anomalies incl. 2090, 1165, 583 and 519 ppb gold in heavy minerals concentrates) and a total of 57 outcrops were mapped of which 48 were sampled. Moreover, 90 mineralized boulders were sampled and samples sent to Val d’Or ALS CHEMEX laboratory and assayed for gold (AA23) and multi-element package (ME-ICP 41), with fourteen (14) blanks.

The technical content of this press release was prepared by M.J. Girard, 43-101 QP.

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