ScoleciteHere we have one of the extensive zeolite family of minerals that usually precipitates from

ScoleciteHere we have one of the extensive zeolite family of minerals that usually precipitates from warm mineralised fluids in volcanic settings, circulating in the Earth in heated convection cells. it was first described in 1813 and named after it’s pyroelectric reaction in the flame of a blowpipe (which used to be a standard mineralogical test way back when, in this case a voltage is generated across the crystal when heated). It is a secondary mineral, growing in cavities within the lava such as gas bubbles. It also occurs in metamorphic rocks, when fluids released from higher temperature rocks below during their transformation by heat and pressure percolate upwards and precipitate their chemical contents upon encountering different temperature or chemical conditions.It usually grows as sprays of needle shaped crystals (called acicular) with lines called striations running down the faces parallel to the long axis, or fibrous aggregates. The usual colour is white but pink or salmony also occurs, as do red and green. Yellow or brown fluorescence is common, caused by electrons getting excited by UV light and jumping up an energy level, then releasing the energy as visible light. It can be very brittle despite its Mohs hardness of 5.5, so specimens should be handled and stored with care to prevent damage and extraction from the hard mother rock is delicate at best.First discovered in Germany famous localities include Iceland, Brazil, California, the Isle of Skye in Scotland and the region around Nassik and Poona in India where the vast basalt outpourings of the Deccan Trapps are sources form many magnificent zeolite specimens, though it is a common mineral known from many localities. The orange spray with chalcedony balls (microcrystalline quartz, the shape is known as botryoidal) came from India and measures 4x3x2cm.LozImage credit: Quebul Fine Mineralshttps://www.mindat.org/min-3594.htmlhttp://bit.ly/2BA8cxYhttp://www.galleries.com/Scolecitehttp://www.minerals.net/mineral/scolecite.aspx -- source link

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