A new acquaintance, Alex Acevedo, brought to my attention a new discovery in Australia of an exceptionally large garnet crystal. He reports an unconfirmed find of a single crystal found that measured 60 meters wide by 40 meters high! Apparently the Australian government has stopped all work at the site until they can determine what to do with this extraordinary discovery.
Extraordinary? Yes extraordinary. Until this new discovery, the largest documented (and proven) garnet crystal on record was 2.3 meter garnet. It measured 10 cubic meters in volume and the weight was estimated to be 37,500 kilograms. This and other large crystals are summarized in an article entitled The Largest Crystals by Peter C. Rickwood in American Mineralogist, Volume 66, pages 885-907, 1981.
It is a thorough article that covers the largest crystals of most common minerals. The largest crystal documented of any mineral is a beryl crystal from Malakialina, Malagasy Republic that measured 18 meters long, 3.5 meters diameter, estimated volume of 143 cubic meters and an estimated weight of 380,000 kilos.
The article illustrates well that the largest crystals of a particular species may not be very large when compared to other mineral species. The following are some examples:
|Mineral||Largest Crystal Confirmed|
|Stibnite||60 x 5 x 5 Centimeters|
|Galena||25 x 25 x 25 Centimeters|
|Corundum||65 x 40 x 40 Centimeters|
|Fluorite||2.13 Meters Diameter|
|Calcite||7 x 7 x 2 Meters|
|Gypsum||3.05 x .43 x .43 Meters|
|Wulfenite||61 Centimeters Diameter|
|Spodumene||14.33 x .8 x .8 Meters|
Possibly the largest crystal ever found, as of 1981, was a single crystal of microcline from the Devils Hole Beryl Mine in Fremont County, Colorado. Miners exposed a single crystal that was estimated to measure 49.38 meters long, 35.97 meters high and 13.72 meters deep, with an estimated volume of 6214.41 cubic meters and estimated weight of 15,908,890 kilograms. However it was unclear if the entire mass was a single crystal and the exact dimensions are inferred from reconstruction.
Closer to home in New England, the largest garnet crystal ever found at the Barton Mine, Gore Mountain, North Creek, NY was 0.91 meters diameter and weighed an estimated 1,544 kilograms. And of course there are the well known beryl crystals from the Bumpus Quarry, Albany, Maine. As I recall, the largest crystal was 18 feet long. Two sections of these beryl crystals can be seen on the north side of the American Museum of Natural History in an area used as a dog walk. Unfortunately the weathered green exterior of the crystals now has a yellow stain around the base because of the dogs' apparent fondness for these crystals.
If you are interested in learning more about large crystals, their occurrences, and other details, you can get a reprint of the article from American Mineralogist, 1015 Eighteenth Street, NW, Suite 601, Washington, DC 20036.
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