Wonogiri Project
Minerals: Gold and copper, silver, base metals
Location: Central Java Island, Indonesia
Area: Two prospects:
Karang Tengah: 2,399.14 ha (5,928.38 acres)
Tirtomoyo: 4,896 ha (12,098.23 acres)
Status: Surface prospecting and regional BLEG/stream sediment sampling
Ownership: 100% by PT. Selatan Arc Minerals (Southern Arc)
Southern Arc's Wonogiri project is located in Wonogiri Regency in Indonesia’s Central Java Province, immediately adjacent to East Java’s Pacitan Regency. Southern Arc has been awarded two kuasa pertambangan (KP) within Wonogiri: Karangtengah and Tirtomoyo.
The Karang Tengah KP is within the villages of Karang Tanah, Hargosari and Purwoharjo in Karang Tengah Subdistrict. The Tirtomoyo KP is situated in an area centred by the village of Tirtomoyo (see maps page). Access to the property is via a sealed road approximately one hour's drive from Wonogiri Town, the administrative centre of the regency. Within the property access is limited to a network of unsealed tracks and footpaths.
The area is rugged, with steep relief and incised valleys. The elevation ranges from over 200 m to 1,004 above sea level. The majority of the area is covered by local rice cropping and vegetable cultivation. Approximately 35 percent of the property is covered in Pinus radiate and is classified as Limited Forestry Production status by the Forestry Department. There are no Protected or Conservation Forestry designated areas within the property
Status:
Southern Arc acquired the Karang Tengah KP in the Wonogiri property on July 21, 2008 and Tirtomoyo in late November 2008. Both KPs are in the first year of the General Survey Period. The KP licenses issued by the Wonogiri Rgency are valid for twelve months and can be extended for a further 12 months as part of the General Survey conditions of the license. However, following the enactment of Indonesia's new mining law on January 12, 2009, the Department of Energy & Mineral Resources has indicated that KPs will transition automatically into a new mining business license (IUP).
Economic Products and Production
The area has been known historically to have gold, other precious metals and other moderate to high base metal mineralization. Van Bemmelen (1949) reports from the district of Japanese historical exploitation of quartz base metal sulfide veins (0.3 to 2.5m) hosted by propylitized Tertiary volcanics. Veins have been traced for hundreds of metres, along a NNE-SSW trend, and contain copper-bearing pyrite, sphalerite and galenite. Previous assays of vein materials reported values ranging from 1.08 to 9.6% Cu, 2.0 to 9.36% Pb, 14.0 to 19.6% Zn, 0.1 to 15.0 g/t Au and 27 to 96 g/t Ag.
It has been previously explored and mined by the Dutch and later by the Japanese during the Second World War. It remains highly prospective with some artisan miners still exploiting the mineral resources in the area to this day.
Historical Mineral Exploration in Wonogiri
Historical Dutch literature (Van Bemmelen, 1949) reports evidence of skarn mineralization, along with inferred porphyry-style veining in the area. Aside from historical Dutch and Japanese activities, only limited surface prospecting has occurred over the property in the last 10 to 20 years. Inferred porphyry Cu-Au style mineralization based on regional drainage sampling signatures (Au, Cu, Zn, As and Mo stream sediment geochemistry) was established by a joint Korean-Indonesian government geochemical mapping program in the mid-1990s.
The two KPs were previously explored by the state-owned company Timah Tbk (1998-2002) under a large super KP license. However, little exploration activities were actually carried out by the company.
A subsequent intra-government geochemical mapping program (JICA-SDM) in 2002 reported local artisan mining of quartz-base metal veins and stockworks hosted by mixed clay-sericite altered volcanics. Samples collected reported values to a peak of 0.70 g/t Au and 2.4% Cu.
The state Bureau of Mineral Resources (SDM) undertook limited surface prospecting in the immediate KP areas in 2005. Selective stream sediment samples, along with ridge and spur soil and outcrop samples, were collected. Available assay results reported samples of quartz-base metal sulfide veins to a maximum of 6.34 g/t Au, 10.5% Cu and 0.99% Pb, whilst soil samples were of low tenor. Sampling of local artisan mining reported an average grade of 30 g/t from 'ore' material.
Previous site visits by Southern Arc personnel noted the presence of high sulfidation veining overprinting earlier porphyry Cu-Au mineralizing events, somewhat analogous to the Selodong Prospect. The geological setting is favourable and akin to the Selodong-Pelangan district. Furthermore, there is an inferred Cu-Au porphyry signature from regional drainage sampling carried out by the joint Japanese-Indonesian geochemical sampling program.
Access
Wonogiri is located on the southern coast of central Java, a very well developed part of the country, with good paved/sealed roads and advanced, modern social and industrial infrastructure. It is located on the limestone hills Gunung Sewu around 30 km southeast of the large city of Solo (also more formally known as Surakarta).
