The gemfields of the New England region of northern NSW are noted for their diverse geology and rich mineral resources. Minerals found include granite-related cassiterite, tungsten, molybdenum, gold, silexite and silver-rich lead, zinc and copper as well as alluvial deposits of tin, sapphires and diamonds. Commercial gemstone mine production has concentrated on sapphire but there has been mining and exploration activity focused on emerald and diamond.
For those interested in learning more about the geology of this region, just came across a very interesting article on the geology of the region. Published online in the latest edition of the Geological Survey of NSW (No.121, July 2006), this article by RE Brown (NSW DPI) reports on interpretation of new airborne magnetic and radiometric data covering the Inverell and Glen Innes area.
While this article is quite lengthy and very detailed, it has some very interesting information on the geological processes responsible for the mineral resources in the area. This airborne survey provided high resolution geophysical data of the Inverell-Glen Innes region – preliminary interpretation of the data has resulted in a range of significant conclusions that have contributed to improved understanding of the geology, geological history and prospectivity of the area.
The article covers most of the major geological formations of the area and discusses importance for prospecting and exploration of various minerals. The section relating to sapphire is toward the end of the article. Previous hypotheses about the Maybole volcano (south-west of Glen Innes) and the Swan-Brook/Kings Plains vent complex as the sources of the richest sapphire deposits have been confirmed by this more detailed geophysical data (see page 29 for interesting diagrams of sapphire occurrence). The new information has also given some suggestions on new areas for diamond exploration – previously concentrated around the Copeton area of Inverell.
Non-geologists may find this article heavy-going (we certainly found it a challenging read), but hopefully might be worth a skim through for anyone interested in how these fascinating gemstones and minerals have come to be found here.
Cheers for now from Aussie Sapphire
(Lightning Ridge article coming up next)