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May 06, 1998
Tiris Project, Sumatra, Indonesia Low-Sulphidation Epithermal Gold System Recognized
Tony Climie, President of Mindoro Resources Ltd. ("Mindoro"), announces further encouraging exploration results from the Tiris CoW, Sumatra, Indonesia, which is held 100 percent by Mindoro.
Mindoro's March 2, 1998, news release described an unusually large and strong gold stream sediment anomaly with accompanying silver, copper and zinc anomalies, now referred to as the Harimau Anomaly. In summary, the greater than 1,000 parts per billion (ppb) (1 gram per tonne (g/t)) gold contour covers seven unrelated drainage systems, extending over an area of 4 kilometres by 3 kilometres and is still open to the south and east. The anomaly was defined by 288 stream sediment samples which were analysed by Intertek Testing Services (Bondar Clegg) in Jakarta.
Twenty of the original samples were checked by an Australian laboratory, Chemnorth Pty. Ltd., an affiliate of Assaycorp P/L. Gold was analysed by standard fire assay/AAS techniques to 1 ppb detection limit (with repeats for high grades). Values ranged from 10 to 20,000 ppb (20 g/t) gold. The Chemnorth results, while statistically higher than the original Intertek results, reflect the same relative contents of gold.
A reconnaissance follow-up visit was made to the Harimau Anomaly by Tony Climie, P.Geol., of Mindoro and a geologist from PT Handal Srirajasa, Mindoro's Indonesian consultant, to carry out a preliminary appraisal of its significance. Outcrop is confined to the stream channels, which are up to one kilometre apart, and is non-existent between these. Hence, currently available geological information is fragmentary. Geology consists of pyroclastics, hydrothermal breccias and reworked pyroclastics, intruded by felsic dykes and andesitic stocks. The pyroclastics are dacitic in composition and include air fall crystal tuffs, ignimbrite and vitric tuff. The reworked pyroclastics are thought to be of lacustrine origin.
Petrologic work carried out on ten rock samples by Dr. L.A. Paterson of the Mineral Services Division of Kingston Morrison, Auckland, New Zealand, indicate that several alteration events have affected rocks in the Harimau Anomaly. Alteration in the pyroclastics/reworked pyroclastics and hydrothermal breccias is strong to intense and on a multi-kilometre scale. Alteration styles include propylitic, phyllic, adularisation and argillic. The earliest events were propylitic and phyllic. These are overprinted by adularisation and intense silicification events as matrix replacements and veining, which are inferred to have occurred at shallow levels. Hydrothermal boiling is inferred to have occurred during adularisation. At least two hydrothermal brecciation events have occurred at a late stage, one accompanied silicification, the other associated with adularisation. Extensive sections of the stream channels, over hundreds of metres, and in several drainages, exhibit intense argillic alteration. These argillic zones consist solely of white clay with abundant limonite mottles which are believed to be derived from sulphides.
Nineteen rock grab samples were also collected to establish gold background and grades in various lithologic and alteration types. The rocks were analysed by Intertek Testing Services (Bondar Clegg) in Jakarta for gold using the standard fire assay technique with AAS finish. Detection limit is 0.005 ppm. Results ranged from 0.009 ppm (g/t) to 1.61 g/t and averaged 0.203 g/t. The 1.61 g/t sample was hydrothermal breccia float collected in a stream channel approximately 200 metres from a sample analysing 3.7 g/t gold, which was collected by a prospector during the initial stream sediment geochemistry program. A rock float sample analysing 1.2 g/t gold was collected in a separate drainage system approximately 600 metres to the east. In the latter drainage, a prospector had previously located a float sample containing 1.6 percent copper and 340 ppm (g/t) silver.
Based on initial reconnaissance work, the Harimau Anomaly is interpreted to reflect a strong to intense, low-sulphidation epithermal system. Significantly gold-mineralized float have been obtained from wide-spaced streams, however, due to the intense alteration and deep tropical weathering, no reliable geological or rock analytical information has yet been derived from the vast majority of the anomaly. The Harimau Anomaly is still open and clearly represents a very high potential gold prospect.
Dr. Paterson notes similarities between features observed in the Harimau Anomaly and the producing Round Mountain Gold Mine, Nevada. These similarities include a pile of pyroclastics and widespread propylitic alteration overprinted by quartz-adularia-sericite alteration. The Round Mountain deposit is hosted in a poorly welded ignimbrite, with some gold concentrated in cooling joints, veins and hydrothermal breccias, and the bulk of the gold disseminated throughout the ignimbrite. Round Mountain produced more than 3.6 million ounces gold through to 1997, and as of that date, had reserves of over 10 million ounces at approximately 1 g/t and over 10 million ounces silver. Early production was at higher grades.
During the initial stream sediment program, a prospector located rock float, assaying 11.7 g/t gold, two kilometres west of the Harimau Anomaly. It is not known whether this is derived from the Harimau Anomaly, or another target. There are three other geochemical anomalies on the Tiris CoW, defined by the Japan International Cooperation Agency, which are yet to be followed up, and which are also considered high priority targets.
A considerable amount of detailed and systematic exploration will be required to define the extent, nature and economic potential of the Harimau Prospect and other targets on the CoW. On receipt of results from reconnaissance geochemical and geological programs currently in progress over the remaining anomalies, an exploration program will be designed to establish this economic potential. It is expected that detailed evaluations will commence in June, 1998. Mindoro is extremely encouraged by results to date.
Mindoro is a well-financed, Canadian mineral exploration company focussing on gold and gold-copper exploration in Asia and operates projects in the Philippines, Myanmar and Indonesia. Mindoro has 13,515,000 shares issued and outstanding and working capital of approximately $2,600,000.
The Alberta Stock Exchange has neither approved nor disapproved the information contained herein.
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