This specimen was recovered from the Nigretta Falls (previously named the Upper Wannon Falls), Victoria. The falls are fed by the Wannon River that has its head waters in the Grampians mountains. Approx. 10km upstream of the Wannon Falls, Nigretta is a multi-channel segmented cascade of smaller drops and bounces guided by patterns of joints in a much older (Devonian) rhyolitic volcanic rock. Both the Wannon and Nigretta Falls are iconic landscape features, entrenched in the history and identity of the region. These falls are particularly rare as they are the product of volcanic activity, which is unique in the context of the Volcanic Plain of Victoria. Waterfalls of this capacity are generally associated with the Uplands areas of Victoria, rather than the edges of the Volcanic Plain. This specimen is part of a larger collection of geological and mineral specimens collected from around Australia (and some parts of the world) and donated to the Burke Museum between 1868-1880. A large percentage of these specimens were collected in Victoria as part of the Geological Survey of Victoria that begun in 1852 (in response to the Gold Rush) to study and map the geology of Victoria. Collecting geological specimens was an important part of mapping and understanding the scientific makeup of the earth. Many of these specimens were sent to research and collecting organisations across Australia, including the Burke Museum, to educate and encourage further study. A solid, dark grey mineral specimen with pale terracotta coloured inclusions. Rhyodacite is a volcanic rock intermediate in composition between dacite and rhyolite. Rhyodacites form from rapid cooling of lava relatively rich in silica and low in alkali metal oxides.GEOLOGICAL SURVEY / R / S 55 FELSTONE PORPHYburke museum, beechworth, indigo shire, beechworth museum, geological, geological specimen, porphyritic rhyodacite, lava, nigretta falls, upper wannon falls, dacite, rhyolite, volcanic geology

This specimen was found in Harcourt, Victoria. Harcourt is a small historic gold rush town located in a valley at the foot of Mount Alexander (741 m) in the Central Highlands of Victoria. In recent times the goldrush origins of the town have been replaced by a district known for apples, cider and wine. The Traditional owners of Harcourt are The Dja Dja Wurrung people. Granodiorite is a coarse-grained intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. Granodiorite has greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase. This piece is of significance due to its provenance in Harcourt, Vic. Granodiorite is commonly produced in volcanic arcs, and in mountain buildings where it emplaces as large batholiths in mountain roots. Granodiorite is the plutonic equivalent of dacite. This specimen is part of a larger collection of geological and mineral specimens collected from around Australia (and some parts of the world) and donated to the Burke Museum between 1868-1880. A large percentage of these specimens were collected in Victoria as part of the Geological Survey of Victoria that begun in 1852 (in response to the Gold Rush) to study and map the geology of Victoria. Collecting geological specimens was an important part of mapping and understanding the scientific makeup of the earth. Many of these specimens were sent to research and collecting organisations across Australia, including the Burke Museum, to educate and encourage further study.Granodiorite is a coarse-grained intrusive igneous rock similar to granite, but containing more plagioclase feldspar than orthoclase feldspar. According to the QAPF diagram, granodiorite has a greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase.GRANDIORITE. / Locality: / Harcourt, Victoria / Other label: Geological survey / R S / Loc Harcourt quarries [?] Alexander / 1/4 Sheet. | 4 | Granite /granodiorite, granite, burke museum, harcourt, coarse-grained, igneous, plagioclase feldspar, orthoclase feldspar, quartz, mount alexander, the dja dja wurrung people, the traditional owners, central highlands of victoria, gold rush