The rock used to make this sculpture is Black Hill Granite and comes from Black Hill located approximately 110 Kilometres northeast of Adelaide.
The igneous rock Norite is a variety of gabbro and is of restricted occurrence in South Australia.
Known commercially as "Black Imperial Granite" this deposit is being quarried for use as an ornamental facing stone in many local and interstate buildings like State Library, M.L.C. and others in Adelaide, also the National Library in Canberra.
The rock weathers in a similar fashion to Granite and the outcrop is a hill surmounted by rounded boulders (Tors) rising 15 to 30 metres above the Murray plains.
Igneous rocks of the Plutonic(intrusive) type, other than granite are rare in South Australia, except north and northwest areas.
This rock is useful both academically for study and commercially as a facing stone because of the remarkable freshness of the minerals in the main body beneath the weathered crust.
It consists of coarse interlocking crystals of labradorite felspar (50%of total rock), clino and ortho-pyroxenes (30%), Biotite (8%), opaque iron oxides and interstitial orthoclase and quartz.
South Australia Mines Department geologists estimate that there are at least six million tonnes of masonry grade rock above plain level and an additional four million tonnes for every nine metres below plain level.
Near GZ you will find 2 sculptures,You are welcome to log a "Found it" log when you message or email the answers for the following questions. any "Found it" logs without the answers being sent will be deleted.
Q1: Was the 2 sculptures made from the same rock or 2 different rocks and how do you come to this conclusion?
Q2: How is this rock useful in a commercial way?
Q3: Did the artist scribe their name into the piece, if yes, where?
Q4: How much masonry grade rock is at Black Hill?