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The Beechworth Burke Museum
Geological specimen - Amazonite, unknown
Amazonite is classed as a Tectosilicate and is part of the Feldspar group of minerals. Amazonite forms in a triclinic crystal structure and its chemical formula is K(AlSi3O8). In appearance, Amazonite can range from shades of green to green blue to blue, and often with white streaks or veining. The greenish colour is believed to come from the small amount of lead contained in its composition. Amazonite is named after the Amazon River due to its colour and similarities to another rock found along the riverbanks, although Amazonite is not actually found at or near the Amazon. Although less commonly used in jewellery today, Amazonite has been mined and used by humans for thousands of years and Amazonite jewellery from at least 2000BCE have been discovered in North Africa. Amazonite is found in many locations around the world including Brazil, Peru, Ethiopia, Canada, Russia, Mozambique, Myanmar, Pakistan, China, Madagascar, and the United States of America. This specimen most probably comes from the U.S.A., Amazonite is found in several US states particularly in Colorado, Virginia, Pennsylvania. This specimen is of both scientific and historic significance as a striking blue green example of Amazonite mined prior to 1868 in the United States of America, most likely from Colorado, Virginia, or Pennsylvania. These three states are all locations of significant Amazonite deposits. 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 palm-sized Feldspar mineral specimen from the Tectosilicate class in shades of blue-green with white veining.Existing label: green/blue Feldspar / "amazonite" / possibly USA geological specimen, geology, geology collection, burke museum, beechworth, tectosilicate, amazonite, feldspar, triclinic crystal structure, amazonite usa, amazonite colorado, amazonite virginia, amazonite pennsylvania -
The Beechworth Burke Museum
Geological specimen - Garnet (red crystals) in galena (silvery metallic) and green feldspar, Unknown
Garnet is a popular gemstone used in jewellery due to its hardness and durability. There are about 5 varieties of Garnet, which distinguish the colour of each stone. In Australia mostly Pyrope and Aimandine varieties are found; Pyrope, which is blood-red to black and Aimadine, which is brownish-red to black. Other varieties are rarely found in Australia. The garnets visible in this specimen are likely Pyrope. Galnea is the natural mineral form of lead sulphide and has had various uses throughout history; from makeup to car batteries. It was first mined in South Australia in 1841. Green feldspar is an amazonite mineral, a variety of the potassium feldspar called microcline. This particular mineral is considered uncommon. It has been used in jewellery throughout history. It is likely that this specimen was found in Broken Hill, NSW, presumed due to findings of specimens with similar combinations. Broken Hill is Australia’s longest-lived mining city. The city’s fortunes have come and gone against an extreme economic background of boom and bust which continues today.This geological specimen is a rarity, given that is formed of three distinct minerals and the richness of colour that remains visible in this item attests to the strength of each structure. As we cannot pinpoint exactly where this specimen was found further research can only strengthen what is known about mining within Australia. As such the item is significant due to its scientific rarity and its ability to represent three specimens in one. A solid palm-sized mineral that features shades of grey, red and green. garnet, galnea, green feldspar, minerals, mining, rare specimen -
The Beechworth Burke Museum
Geological specimen - Green Feldspar (orthoclase)
Feldspar, derived from the German word feldspat, is a group of minerals which is the most common mineral group found on Earth, making up more than half of the planet's crust. The major rock-forming minerals in the Feldspar group include albite, anorthite, orthoclase and microcline. (Mindat, Feldspar Group). Orthoclase is part of the Feldspar Group subgroup, Alkaline Feldspar, which are known to be poor in calcium, and mostly rich in potassium. It is further also considered to be a K Feldspar, a subgroup of Alkaline Feldspar that are Potassium-dominant with variable crystal symmetry and Al-Si ordering state. Orthoclase are most commonly Colorless to white, Greenish white, Grayish yellow, or Pale pink and transparent to translucent with slightly pearly cleavage. The mineral rates at a 6 on the Mohs Hardness Scale. (cannot be scratched with a knife, but scratches glass with difficulty). The stronger green colour of this particular specimen is distinctive to the Broken Hill region (where it was found), and due to a small amount of lead. (BB) Its qualities find it misidentified at times as as microcline variety amazonite. Broken Hill is one of the world’s richest lead-zinc-silver deposits. The huge, 300-million-tonne orebody was discovered in 1883 and the superb mineral specimens attract collectors from around the world. (Australian Museum, Minerals from Australia: Australian mining regions)While feldspar is not by any means rare, this particular specimen has qualities distinctive to the Broken Hill mining district, with these properties leading at times to the mineral's misidentification. This creates potential for further study and identification of these mineral deposits through methods such as microscopic twinning, or using the position of certain d values in XRD patterns to calculate the degree of disorder of a K-feldspar, as discussed on the Mindat website (Mindat.com, Orthoclase:About Orthoclase). 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 small aluminosilicate mineral composition which is primarily pale green and blue-grey in colour with traces of beige and white throughout. Note: green plumbian orthoclase (aka green feldspar) is an indicator mineral for the Broken Hill style lead-zinc deposits.N/Abroken hill mine, geological specimen, minerology