Chrysanthemum stoneThis beautiful rock specimen comes from deposits in Hunan province, China. No, th
Chrysanthemum stoneThis beautiful rock specimen comes from deposits in Hunan province, China. No, that’s not actually a real flower; this is all geology.The black rock itself is a piece of limestone. Although limestones generally are lighter in color, this one is quite black because of the presence of substantial amounts of organic carbon. This rock is Permian in age, from a time when many areas that today make up China were offshore or underwater plateaus.The white pattern on the rock is formed of crystals of celestine (or celestite), a strontium-sulfate mineral. Celestine commonly forms elongate crystals of the form seen here, although these are fairly rare in that they’re so thin and on the surface of another rock.Strontium is often concentrated in carbonate rocks and probably grew on these larger limestone surfaces as a consequence of flowing water after the rocks were deposited; a small crystal could nucleate at the center of the flower and crystals would then grow outwards from that center point.-JBBImage credit:http://www.fotopedia.com/items/flickr-6452804877http://www.webmineral.com/data/Celestine.shtml -- source link
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