Mineral investigations near Bodmin, Cornwall. Part 5, the Castle-an-Dinas wolfram lode

A gridded soil survey to the south of Castle-an-Dinas Wolfram Mine produced a pattern of anomalies indicative of at least two sub-parallel zones of tungsten veining extending some 300 m south of the St. Columb- Belowda road. Between the Royalton elvan and the northern edge of the Goss Moor alluvium there is a broad area of anomalously high tin values. Percussive drilling later confirmed widespread tin mineralisation beneath the soil anomaly but in the case of tungsten the in-situ mineralisation was confined almost entirely to one zone and in that to within about 50 m south of the road. This zone can be correlated with the Wolfram Lode in the mine. To the north of the former workings three sets of traverses, spaced out over a projected strike stretching about 1100 m from the most northerly stoping, were also sampled from fairly short percussive drillholes. Over this distance it was possible to trace two zones of tungsten-tin mineralisation, sometimes with copper, one correlatable with the Wolfram Lode and the other sub-parallel and some 90 m to the west. Close to surface these lode extensions are sub-economic but, from the evidence accumulated to date, it appears that viable ore grades are located only in the metamorphosed slates within about 200 m from the granite contact. It is believed that the potential south of the old workings can be estimated at about 1000 tonnes of recoverable tungsten metal. To the north, however, the strike length of possible mineralisation is less predictable, but there is little doubt that this area offers the better target for exploration.