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Project Review 2002
History
Cominco Limited staked portions of the current Foremore Property area after the discovery of a gold-rich (5.2 oz./ton Au) quartz boulder and several massive sulphide boulder fields during helicopter reconnaissance in 1987. Subsequent exploration work by Cominco was conducted to determine the source of over 1000 VHMS mineralized boulders in the North (NBF), South (SBF), Side Glacier Boulder Fields (SGBF) and East Boulder Field (EBF). Strong UTEM geophysical conductors located under the More Glacier were subsequently diamond drilled with a total of six holes that failed to intersect mineralization of interest. Cominco carried out a total of over C$2,000,000 of work on the property during 1987--1992 and subsequently in 1996 prior to the claims lapsing in 1999. Roca's property vendor, L.B. Warren staked the large land package, and Roca can earn a 100% interest in the property by conducting exploration work and by making cash and share payments.
Roca has recently added to the total tenement area of 155 sq.km by staking additional claims to include other areas of interest.
Compilation And Field Work 2002
In May 2002, Roca began detailed research on the Foremore area geology, a comprehensive data compilation and an air-photo interpretation study. That work resulted in the definition of a number of new targets areas for mineralization that had not been recognized or pursued by Cominco in the past. Equity Engineering Limited was then contracted to carry out a summer 2002 field program that consisted of geological mapping, prospecting and geochemical sampling specifically focused at the target zones identified from our review. In addition to their efforts during the field season, Equity also prepared a qualifying report on the property which was summarized and filed with Roca's IPO prospectus offering.
As a direct result of our targeting efforts and successful field activities, a number of mineralized zones, comprising several different mineralizing styles were identified on the property. An unqualified success in terms of its outcome, the discovery of the SG zone as a bedrock source area for one of the boulder fields has become a primary target for Roca. It should be noted that this discovery is the first, in the history of the property to locate source rocks for one of the mineralized boulder fields. It is our belief that, having discovered one such source, others must also be present to account for the wealth of mineralized boulders on the property. A review of our 2002 work program is included in the BC Ministry of Energy and Mines, Resource Development Division Exploration and Mining in British Columbia 2002. Related Extracts from this summary are provided in the file BCMEM-2002Report.pdf - available under the "Articles and Comments" menu heading.
VHMS Targets (SG Zone, SG East, North Zone)
"In 2002, exploration significantly advanced three mineralized zones on the Foremore Property with the potential to host economic VHMS mineralization: the North, (and newly discovered) SG Zone and the SG East Zone." Equity Engineering Inc. (2002)
- SG Zone
During the course of the 2002 field program, the SG (Side Glacier) Zone (hypertext SG Zone map) was discovered and recognized as VHMS style mineralization. Perhaps the most meaningful part of this discovery came late in the field season when Roca undertook a bedrock blasting/trenching program to more fully expose massive to semi-massive sulphide discovered in outcrop.
Mineralization is hosted in a quartz-sericite±chlorite altered intermediate to felsic volcanic rock. Layered and remobilized heavily disseminated to massive Zn-Pb-Cu-As mineralization is common with one specimen assaying 20.1 g/t Au and 23.8% Zn-Pb. Mineral textures and elemental abundances are consistent with VHMS deposition.
As previously noted the SG Zone is believed to be the source of the boulders found and assayed by Cominco at the SGBF. Cominco sampled eight boulders in this field returning an average assay shown in the table below. The SG Zone is open along strike north easterly and south westerly and down dip to the north.
Side Glacier Boulder Field Assay Results (Cominco)
| Boulder Type |
Au (g/t) |
Ag (g/t) |
other |
| Altered Felsic Volcanics (8 samples) |
7.3* |
58 |
9.3% Zn+Pb |
Note *: Fire assay of 4 samples
- SG East Zone
The newly discovered SG East Zone is located approximately 200m southeast of the SG Zone and mineralization consists of stratiform heavily disseminated to massive pyrite, magnetite with minor chalcopyrite mineralization hosted in a dark grey to black limey argillite. The mineralization is anomalous in Au, As, and Zn.
- North Zone
Mapping and prospecting at the North Zone traced lead-zinc-silver mineralization in quartz-sericite-pyrite schists interfoliated with chloritic schists. Roca's 2002 work shows that mineralization consists of thin foliation-parallel laminations and disseminations of pyrite, sphalerite and galena with lenses of semi-massive to massive pyrite in the quartz-sericite-pyrite schist. The North showing is associated with lead-zinc-barite-silver anomalous soil geochemistry and a strong UTEM conductor, and has not been trenched or drill tested to date.
The North Zone is believed to be adjacent to one of the source areas for the North Boulder Field (NBF). Cominco sampled two types of boulders identified in this area producing the following average assays;
North Boulder Field Assay Results (Cominco)
| Boulder Type |
Au (g/t) |
Ag (g/t) |
other |
| Layered (29 samples) |
1.0 |
96 |
13.7% Zn+Pb |
| Feeder (12 samples) |
1.5 |
186 |
8.5% Zn+Cu |
Epigenetic Gold Targets (Westmore, Hanging Valley)
- Westmore Gold Zone
The Westmore Gold Zone is an extensive area containing Au-bearing sheeted quartz veins hosted predominantly in post-Triassic intermediate to granitic intrusives (Westmore Stock), and less so in Devonian-Mississippian lithologies. Cominco personnel found float boulders assaying as high as 162 g/t Au, and in-place grab samples running > 20 g/t Au. Roca collected a float sample returning 17.05 g/t Au and a chip sample containing 2.27 g/t Au and noted visible gold.
The vein sets trend east-west to southeast-northwest and are 0.25 to 2m in width. Thicker veins are composed of milky white quartz with minor coarse grained pyrite and thinner veins locally contain abundant sphalerite, galena, and chalcopyrite. At least two generations of veining are present at the Westmore Au Zone.
- Hanging Valley Targets
The Hanging Valley is a relatively broad open valley rimmed by variably altered and mineralized carbonate rocks. Widespread mineralization is present as Au-rich sulphide lenses and veins that generally occur as foliation parallel structures or as thin shear zones. Gold grade as high as 93.7 g/t (1m chip by Cominco) and 81.7 g/t (Roca grab) are present. Devonian-Mississippian limestone and felsic volcanics will be prospected as potential source rocks for the South Boulder Field (SBF).
South Boulder Field Assay Results (Cominco)
| Boulder Type |
Au (g/t) |
Ag (g/t) |
other |
| Massive Sulphide (53 samples) |
n/a |
102 |
11.3% Zn+Pb |
Summer 2002 fieldwork provided new insights and complimented our geological database with respect to epigenetic Au targets on the property (Westmore and Hanging Valley). Further work will also be carried out on these gold-only targets during the Phase I drilling campaign in 2003.
Exploration Potential
The Foremore Property lies within an extremely rich metallogenic belt that is a direct result of prolonged island arc volcanism. This world-famous belt hosts a number of very significant present and past producers, displaying a wide variety of genetically related mineralization styles, including:
- Porphyry Copper-Gold-Molybdenum - Schaft Creek, Galore Creek, Kerr/Sulpherets;
- Intrusion related mesothermal veins - SNIP and Johnny Mtn. gold mines, Red Mtn;
- Epithermal gold-silver veins - Sulpherets, Newhawk, Premier Mine, Golden Bear Mine;
- Volcanic Hosted Massive Sulphide - Eskay Creek, Tulsequah Chief, Granduc.
The SG, SG East and North zones share many mineralogical and grade characteristics with world-class VHMS deposits. Au and Ag enriched stratiform sulphide mineralization is hosted in felsic to intermediate volcanics and associated sedimentary rocks.
Past exploration work at the Foremore Project by Cominco consisted of geological mapping, prospecting, rock sampling, soil and stream geochemistry, ground geophysics and diamond drilling. Recent work by Roca has been very successful in targeting and subsequent discovery of significant VHMS mineralized zones. These zones (some with coincident geophysical conductors and geochemical anomalies) will be advanced by trenching and diamond drilling during Roca's Phase I exploration program commencing in June 2003. Concurrent mapping, prospecting and sampling will be carried out to locate the bedrock sources of the North Boulder Field (NBF), South Boulder Field (SBF) and the East Boulder Field (EBF).
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