prehnite


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prehnite

(ˈpreɪnaɪt)
n
(Minerals) a brittle mineral with a greenish tinge
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Major elements concentrations are controlled by the alteration and formation of minerals like feldspar-K, plagioclases, quartz, biotite, amphibole, chlorite, pyrite, wairakite, prehnite, muscovite, epidote, and talc, as reported in CP by Elders et al.
Yellow chalcedony paraded on one necklace with clear rock crystals and peridot, while aquamarine, prehnite, amethyst, and red jade were joined in others.
Both the crown and pavilion consisted of beryl (for emerald substitutes), topaz (for imitations of spessartine, tanzanite, Paraiba tourmaline and rubellite), tourmaline (for another Paraiba tourmaline substitute) and quartz (for imitations of peridot, aquamarine, topaz, morganite, amethyst, ametrine, bicoloured tourmaline and prehnite).
In these rocks, secondary mineral include chlorite, zeolite, prehnite, iron oxides and sericitie that rocks fractures and spaces are filled with minerals.
In most of the cases, but especially in the rocks of intermediate to acid composition, the rocks show moderate to severe hydrothermal alteration, with the development of potassic minerals (sericite, K-feldspar), prehnite, and carbonates accompanied by other secondary minerals (epidote, quartz, chlorite, titanite).
The piece de resistance is a pair of earrings that plays on the complementary colors of green and blue-turquoise, prehnite, iolite and diamonds framed in yellow gold.
Some form when temperatures are in a broad range above freezing; others, like the calcium-aluminum blend known as prehnite, require baking at particularly high temperatures (between 200[degrees] and 400[degrees] Celsius).
Another clue is detection of a mineral called prehnite. It forms at temperatures above about 400 degrees Fahrenheit (about 200 degrees Celsius).
It seems a local collector has been working a seam at the quarry and has dug out beautiful specimens of calcite, quartz and prehnite. Most specimens are quartz-calcite combinations in miniature to large-cabinet sizes, with small-cabinet sizes being the norm.
Chlorite, prehnite, and sporadically developed pumpellyite indicate that the rocks have reached prehniteactinolite facies conditions.
The blocks are serpentinites, dolerites and metagabbros made of hornblende phenocrysts and prehnite. These products of a low temperature static metamorphism were not observed elsewhere in the peninsula.
But there are localities famous for mineral growth right here in Canada, one of them being the Jeffrey Mine in Quebec's Shipton Township, famous for prehnite and the beautiful grossular crystal, a variety of garnet.