Historical Exploration

Geological mapping was undertaken in the Kadiica area in several phases over a long period of time, from 1840 to 1960.

In 1963 an aeromagnetic survey was flown over the eastern part of Macedonia which gave anomalous results for the magnetic field of the Bukovik area. The main source for the anomalies discovered are most likely the presence of rocks with generally high magnetic susceptibility in the area, but part of the anomalous signature is believed to relate to low-order magnetite mineralisation associated with the Kadiica-Bukovik porphyry system.

In 1965 limited exploration was carried out on relatively minor occurrences of lead and zinc in the area.

Between 1967 and 1975 the ferricrete deposits on the southwestern slopes of Bukovik mountain were investigated in detail by the State. An extensive shallow grid drilling programme was undertaken on the main targets, and this was supplemented by underground investigation, involving driving a number of adits, followed by geological mapping and sampling. Arising from this work, an in-situ resource was established in the C1 category, in accordance with the State estimation methodology, totalling approximately 8Mt @ 32% Fe. Metallurgical test work was also undertaken.

In 1984 -1985 detailed geological exploration for copper was undertaken by the State in the locality of Bukovik and Kadiica. This included geological mapping, soil sampling and limited induced polarisation geophysical surveying. No follow-up drilling was carried out. Copies of data from this programme are held by Phelps Dodge and were examined by CSA.

Exploration by Phelps Dodge

As at Osogovo, Phelps Dodge in 2001-02 undertook detailed geological mapping and rock sampling at the Kadiica intrusive complex and surrounding area. In addition, a programme of stream sediment sampling and soil sampling was completed.

The stream sediment programme concentrated on the slopes and fringes of the main Bukovik-Kadiica mountain. A total of 40 samples was collected at approximately 500m intervals along the drainage network. The samples were dried and sieved in Bulgaria before being despatched to the American Assay Laboratories facility in Nevada for assay for a range of elements.

Extensive copper (max. 324ppm) and more limited gold (max. 332ppb) anomalies were detected on the south and west of the mountain, with some molybdenum and zinc support.

A 100m x 50m soil sampling grid was also completed over the central part of the intrusive complex. Restricted anomalies were located for copper (max. 380ppm), gold (max. 267ppm) and for molybdenum, arsenic and lead. Rock grab sampling in the same area identified several samples with low order copper mineralisation, including a breccia boxwork exposure with visible hematite-chalcocite, and one sample with anomalous gold (105ppb).

The ferricrete deposits on the southern and western slopes of the mountain were also sampled to follow up earlier reports of visual identification of supergene copper minerals. 160 rock grab samples were collected and, while anomalous copper was detected, up to 880ppm Cu, no copper sulphide or oxide mineralisation was identified.

Phelps Dodge drilled eight vertical holes in 2002 to test for a large, open pittable, porphyry copper deposit at Kadiica. A hole through the ferricrete deposit failed to intersect any copper mineralisation, but a number of holes drilled through the main breccia stockwork zone did make copper intersections of interest.

Hole PDKC-1, sited within the main mapped breccia zone, near the hematite-chalcocite breccia boxwork, was drilled to a depth of 219.6m. It passed through a 110.3m leached cap into a mixed oxide/sulphide zone with low grade chalcocite-covellite mineralisation. From 132.4m to 153.4m the hole intersected a laminated and silicified dacite porphyry, stock worked in places, with more strongly developed pyrite, chalcocite and covellite. This 21.0m section assayed 0.77% Cu and occurred within a wider zone of 52.3m assaying 0.40% Cu (Table 3).

Hole PDKC-2 was sited approximately 600m to the north of the first hole, within the quartz-porphyry stockwork, but outside the mapped breccia zone. The hole, which was drilled to a final depth of 260.1m, passed through the leached cap to a depth of 139.0m, then through a mixed oxide/sulphide zone with minor chalcocite and covellite, into a less weathered supergene sulphide (primarily pyrite, chalcocite, covellite) stockwork zone comprising dacite breccia and tuffs/metasediments. From 144.0m to 260.1m, a 116.1m interval assayed 0.27% Cu, within which a 20.1m section assayed 0.44% Cu. The hole bottomed in stockwork with low order pyrite, molybdenite, chalcocite and covellite mineralisation and may not have tested the primary hypogene sulphide target.

Holes PDKC 4, 5, 7 and 8 were drilled respectively 850m northwest, 550m west, 850m north-northeast and 300m south of PDKC-1. All of these holes passed through leached zones near surface and into moderately to weakly stockworked intrusives or metasediments, generally containing low-order pyrite-chalcocite-covellite mineralisation in a defined supergene blanket. Some holes did not bottom out of the supergene zone. PDKC-5 also intersected gold traces, with assays up to 112ppb Au.

Table 3 – Selected intersections from the Kadiica drilling programme showing the degree of enrichment of the supergene blanket

Source: The CSA Group,Sirius Competent Person’s Report, May 2005