Mooralla, Southern Grampians Shire, Victoria, Australia
|Latitude & Longitude (WGS84):||37° 20' 49'' South , 142° 3' 4'' East|
|Latitude & Longitude (decimal):||-37.34694,142.05111|
|Köppen climate type:||Cfb : Temperate oceanic climate|
Since the 1960s smoky quartz 'geodes' have been highly sought after from the designated gem collecting site near Mooralla, near the Grampians in western Victoria. The geodes are formed below the surface in weathered greenish-grey rhyolite, known as the Rocklands Rhyolite, which erupted in the Late Devonian period. Decades of collecting have resulted in a landscape of low dumps, partly filled in pits and holes as deep as six metres in an area where good specimens were once recovered from close to the surface.
The predominantly smoky quartz crystals, very dark brown to black in colour, are noted for their transparency and lustre, and often contain wispy swirls and gas bubbles in fluid inclusions. They are found as simple to complex crystals or groups of crystals up to three or four centimetres across and loose crystals, weathered out of the rhyolite, are common. Most valued are spherical geodes up to 10 centimetres across, with one or more crystals attached to the inside walls of the geode.
The inside walls of the geodes are often lined with small opaque and colourless quartz crystals up to a few millimetres long, and sometimes amethystine to pink or lilac quartz of similar size.
Mineral ListMineral list contains entries from the region specified including sub-localities
5 valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
393.3 - 419.2 Ma
|Rocklands Volcanic Group|
Age: Early Devonian (393.3 - 419.2 Ma)
Stratigraphic Name: Rocklands Volcanic Group
Comments: igneous felsic volcanic; synthesis of multiple published descriptions
Lithology: Igneous felsic volcanic
Reference: Raymond, O.L., Liu, S., Gallagher, R., Zhang, W., Highet, L.M. Surface Geology of Australia 1:1 million scale dataset 2012 edition. Commonwealth of Australia (Geoscience Australia). 
|Early Devonian - Late Silurian|
393.3 - 427.4 Ma
|Paleozoic volcanic rocks|
Age: Paleozoic (393.3 - 427.4 Ma)
Lithology: Felsic volcanic rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
Localities in this Region
- Southern Grampians Shire
- Southern Grampians Shire