Oropa reports N. Sumatra gold project activities
Tuesday, July 31 2007 - 09:24 AM WIB
The following is an edited excerpt from ASX-listed mining firm Oropa Limited on Indonesian projects, taken from quarterly report ended 30 June 2007.
Pungkut Gold Project, Sumatra (75%)
An appraisal of Pungkut by Richard Sillitoe (“Sillitoe”) earlier this month has resulted in a re-focus of Oropa’s near term exploration, with the objective of adding additional gold resources to the existing inferred resources, but the greatest potential to substantially add to the resource base exists in other prospect areas such as Sihayo 3, 4 and 5 to the west of Sihayo 1 North and Hutabargot Julu, located to the south-east of Sambung. Sillitoe’s evaluation of Sihayo and Sambung concluded that the gold mineralisation is largely controlled by receptive layers in the Permian limestone-epiclastic sedmentary sequence, supporting previously interpreted shallowly dipping deposit model. This re-interpretation is consistent with the parameters used to wireframe the Inferred Resources of Sihayo 1 North and Sambang.
Sillitoe is a Shell Postdoctoral Research Fellow from London University and from 1971 to the present has worked as an independent geological consultant for numerous international mining companies, international agencies, and foreign governments. He is a widely published, recognized expert on gold and copper-gold mineral deposits.
Sillitoe’s Findings:
(a) Sediment Hosted Gold Prospects
Sihayo 3, 4 and 5 occurs over a 2.2 kilometre trend of jasperoid outcrop and hillfloat. Sihayo 3 rock sampling returned an average of 0.93 g/t Au with a maximum of 4.1 g/t from 25 samples collected, and Sihayo 4 samples (24) average 1.55 g/t with a maximum of 16.5 g/t.
These prospects, which are all at an early exploration stage are considered to offer good potential for additional resource.
(b) Epithermal Gold in Quartz Veins
Hutabargot Julu, for which historical Dutch reports recording vein widths of up to 3 meters averaging 20 g/t has potential for high grade gold ore shoots. Several veins have been traced for up to 3kms in length, and the area is in close proximity to the Sihayo-Sambung resources. Drill testing of the Tarutung prospect has also been recommended, with initial close step-outs from known outcrop.
The Nalanjae, Nalanjulu and Rotap prospects in the South Block contain bonanza gold grade quartz vein floats, which require follow up work.
(c) Porphyry Copper-Gold
Four porphyry copper prospects have been confirmed as worthwhile stand-alone exploration targets that could readily be brought to scout drilling stage. These include Sihayo 2, located 2km northwest of Sihayo 1 North, Singalancar, situated in the western portion of the North Block and Rura Balancing, also in the North Block, plus Namilas which is situated in the South Block. Potassic alteration has been positively identified in outcrop in 3 of the 4 prospects.
Activities – Northern Block:
Sambung:
11 diamond drill holes (749.4m) completed. This drilling, that tested a geophysical Induced Polarisation anomaly to the west of the Sambung Inferred Resource tested discovered extensive but poorly mineralised jasperoid.
Sihayo 1:
4 diamond drill holes (258.8m) completed. Drilling underway testing the strike extension of gold mineralised jasperoid discovered in test pit.
Sihayo 1 North:
2 diamond drill holes (159.65m) Drilling in progress testing north-south trending jasper outlined by mapping.
Sihayo-Sambung Trend
Sambung Geophysical IP Anomaly
Drilling of a large IP geophysical anomaly to the west of and parallel to the Sambung Inferred Resource has confirmed the existence of a near surface zone of jasperoid 100m wide over 200m of strike and up to 30m thick, but of sub-economic grade, although visible gold was observed in several drill-holes. Best intersections include:
SAMDD076: 3m @ 2.17 g/t from 4m;
SAMDD079: 1m @ 172.00 g/t from 3m;
SAMDD082: 1m @ 1.0 g/t from 5m.
No further drilling is planned immediately west of the Sambung resource. However, this drilling has proved the effectiveness of IP geophysics in outlining concealed jasperoid.
Activities – South Block:
Matait
Prospecting in the South Block discovered hill float comprising silica-flooded carbonate sediments with a similar alteration style to the jasperoids at Sihayo-Sambung in the North Block. Assay results returned only low values with a maximum of 0.54ppm Au. No further follow up is planned. (end of edited excerpt)