Silica valleys and hills

Not far along the dirt road towards Corinna, the misty fogs disappeared and the landscape appeared. Sensory overload. So much to see and marvel at. From exposed hills and rocky outcrops with highland grasses eventually we travelled into dense forests.

We were on the lookout for a right hand turn northwards into Norfolk Road (on Google maps) or the Western Explorer Road as it is designated by Tasmanian agencies.  We were not sure if this would be signposted adequately. Care was taken but we turned into an incorrect road well before our desired turn off – which we later found was signposted correctly.

This was a short road which arrived at a quarry for white rock. Quartz like rock was everywhere. Fields of white under a cloudy sky is how I remember that vista. Locally known as the Corinna Mines the name on the entrance sign is Tasmanian Advanced Minerals (http://tasam.com.au/).

Websites refer to it by older names such as the Corinna Silica Mine (Cominex mine). One website provides the following information:

This mine, just north of Corinna, produces silica flour, a very fine grained and very pure form of quartz, in high demand for glass making etc. The silica flour is a residual deposit formed by prolonged leaching of siliceous (siliceous rocks are sedimentary rocks that have silica as the principal constituent) Precambrian (from the earliest period of the earth’s history) dolostones. There are occasional blocks of vein quartz in the silica flour, sometimes smoky and with almost bipyramidal crystals. There are a number of separate deposits in a small area.”

If you want further information, perhaps reading Mineral Resources Tasmania’s 1993 report about drilling around Corinna will be of value. The Apple Isle Prospector website summarised the situation “There are two mines in the Corinna area today: The Grange Resources Savage River iron ore mine, and the Cominex silica mine (red hashing in the picture to the right).”

Corinna_silica mine in red.jpg

Obviously this silica mine has played a significant role in the recent social and industrial history of this part of the Tarkine. A 1995 Mining Resources Tasmania report explains “possible uses for the silica sand were recognised by H. Nolan in the early 1980s.”  The report continued, “The silica flour is 99.9% or more of SiO2 and is suitable for the manufacture of optical fibre, high quality lens glass, silicon chips and lead crystal.” Silica is valuable so I have no doubt the mine will continue operation. An ABC News story reveals a new use in their article Tasmanian silica demand increasing as smartphone screens go ultra HD.

Later that day, when we climbed Mt Donaldson, we looked across to the bald patches in the landscape produced by this mine.

20170305_124942.jpg

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