Don't mine our DOC estate

A couple of years ago Ruth and I did a round day trip on the tops above the Cobb Valley in the Kahurangi National Park. Part of the track overlooked an area I prospected in as a young geologist in the mid 1980s before the area was included in the National Park network by Helen Clark's government. The company I worked for was looking for copper and gold and fortunately, I happily say now, we didn't find anything of significance.   

During our tramp we passed through an area of abandoned asbestos workings. Mining had taken place there on a small scale over the years, initially by hand in the early 1900s and then with bulldozers and heavy machinery in the 1960s. On those exposed sites with lean and mineral rich soil the vegetation re-growth has been slow and the scars on the hillside are still clear for passers-by to see.  

One wonders what sort of landscape 'surgical mining' might leave in similar terrain and how it would look like at the time and in another 50 years. How much interest would visitors to the area have in the ravaged hillside compared to the beautiful bush clad vistas in other directions?  

So what about the government’s proposal for a ‘stock-take’? Bulldozer Brownlee says its “just the mineral search we are promoting, so we can assess the pros and cons of mining any resource that may be present.”  Even if we take this at face value (and that is not my inclination) it begs big questions about the impact of that search - access tracks, sampling trenches, drilling sites and bulk sampling pits. These activities bring to the surface low-grade ore and associated mineralised waste rock.

There is something quite fundamental about the majority of mineral deposits and that is the presence of sulphide minerals. These comprise the ore itself (and importantly the low grade uneconomic margins that would be left un-mined and exposed to the weather), or as an associated waste mineral such as pyrite. Coal commonly also has pyrite rich material associated it.

These sulphides are the source, after oxidation by contact with air or water, of sulphuric acid and the acid mine drainage that has laid waste areas around abandoned coal and metal mines in Australian and the USA. And in just small quantities it makes streams and rivers uninhabitable for their natural biota.

A confounding factor when the mineralised rock is near the surface naturally, is the weakly developed and fragile soils and specialised, often rare, mineral ‘tolerant’ plant species. These twin challenges make the land involved in the mineral search as well and mining both more or less impossible to restore or rehabilitate without many decades of close care and attention.

“We’ll just do a stock-take”. No, Gerry I don’t buy it mate. If you’ll pardon an old mining term, your stock-take is a crock!