Weathered Granite Gravel

About

Weathered Granite Gravel (also know as Decomposed Granite and Granitic Sand) is a classification of gravel that is derived from granite via its weathering to the point that the parent material readily fractures into smaller particles. 

The rock material crushes down into stable granular fine gravel and coarse sand particles, containing a mixture of feldspar, mica, clay, quartz, and plagioclase.

The resulting gravel and sand has practical uses that include its incorporation into pavement construction, paving and driveway materials, landscaping, and gardening materials, as well as various types of walkways, aggregates, tracks, trails, paths, geopolymer concrete, walls and roads. 

The gravel has a rich orange-gold colour and has a fine consistent particle composition.  

Treatments and admixtures such as Ground-granulated blast-furnace slag (GGBFS) and Hydrated Lime (eg. Steel Pave), Ordinary Portland Cement, Fly Ash, Industrial Psyllium Powder, Tall Oil (eg. Soilbond) and Geocells can extend the range of decomposed granite properties, uses and applications. 

Operations at Wootong Vale Granite Gravel Quarry began in 1974 with the quarry was known as "Turner's Pit".

Extractive Industry License No. 1020 was granted to H.F. & R.F. Turner in 1981 with planning development approval granted 14 February 1980.  The weathered granite gravel quarry has remained in operation since that time.

The geology of the quarry is post Cambrian–Ordovician (post 410+/-4 million years). The stratigraphic unit associated with the weathered granite gravel is Hassall Creek Granodiorite (G409). For further details on the geology refer Geological Survey of Victoria 1:50 000 Geological map (NAREEN 7223-3 and part of COLERAINE 7222-4).

X-ray diffraction has identified the following crystalline mineral phases in Wootong Vale DG.
51% Anorthite ((Na0.45Ca0.55)(Al1.55Si2.45O8))
18% Microcline (K0.91Na0.09AlSi3O8)
17% Quartz (SiO2)
5% Muscovite-2M2 ((K,Na)Al2(Si,Al)4O10(OH)2)
1% Montmorillonite-chlorite (Na-Ca-Al-Si4O10-O)
1% Amphibole (Al3.2Ca3.4Fe4K0.6Mg6NaSi12.8O44(OH)4)

Approximately 8-10% is non-crystalline (amorphous).