The isolated town of Broken Hill was built on the worlds largest silver, lead and zinc mineral deposit known as “The Line of Lode”. The mineral seam has yielded more than 300 million metric tons of sulfide ore.
The ore body is hosted within a unit of gneiss known as the Potosi Gneiss. This cream/grey coloured mineral material contains nothing of value. The waste gneiss is known as mullock. The mullock heap a local landmark called That Hill, is a backdrop to the centre of town and huge marker of the town's mining heritage. The heap contains the residue of waste material from over 130 years of mining. The waste is minerals extracted from the depths of the earth and contains no soil.
That Hill is a reminder of the past and a contributor to dust in the town. Ongoing stabilisation of the hill is carried out by spraying a polymer to fix the friable surface. The polymer is stained green to show the location of the polymer.
At the listed coordinates you are standing on the huge mullock heap towering above the city of Broken Hill. Look to the south. Sections of the mullock heap have a green colour.
- Describe the rocks you are standing on. Texture? Size? Hardness? Colour?
- Can you suggest another way of stabilising the mullock heap?
- Why is there is no vegetation growing on the barren mullock heap?