Spessartine


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Spessartine

 

(from the Spessart range in the Federal Republic of Germany), a mineral of the garnet group, a manganese-containing aluminogarnet having the composition Mn3AI2[SiO4]3 and containing typical isomorphic impurities of Fe2+, Mg2+, Ca2+, and Y3+. Spessartine crystallizes in the cubic system, forming crystals typical of garnets or, frequently, compact granular masses. The color varies, depending on impurities, from light pink to red-brown. The mineral has a hardness on Mohs’ scale of 7–7.5 and a density of 3,800–4,280 kg/m3. Spessartine is most commonly encountered in garnet pegmatites, metamorphic rocks, and skarns.

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Colour Gem imitated (ct) 1 Green Emerald 5.35 2 Green Emerald 3.86 3 Blue-green Paraiba tourmaline 1.71 4 Blue-green Paraiba tourmaline 3.36 5 Red Rubellite 4.45 6 Orange Spessartine 4.71 7 Violet Tanzanite 4.49 8 Yellow-green Peridot 8.83 9 Light blue Aquamarine 7.54 10 Light blue Topaz 8.64 11 Orangey pink Morganite 8.21 12 Violet Amethyst 8.66 13 Violet and yellow Ametrine 8.30 14 Red and green Bicoloured tourmaline 8.37 15 Milky green Prehnite 8.48 16 Colourless with Gold-in-quartz 13.79 'golden' inclusions 17 Colourless with Rutilated or 2.29 narrow foil strips tourmalinated quartz 18 Various iridescent Girasol 4.28 Internal features Crown/ In crown and No.
As indicated by the data in Table II, the stone consists of almandine with a spessartine component rather than a pyrope component.
Only a small lot of bizarre, though good-quality, little spessartine crystals was available for sale.
Based on type garnet market is classified into almandine, andradite, grossular, pyrope, spessartine, and uvarovite.
In a second talk, Dr Krzemnicki described items studied recently in SSEF's laboratory, such as sapphires from basaltic deposits in Nigeria, low-temperature heated rubies from Mozambique, heated red spinels from Tanzania, a hydrothermal synthetic emerald weighing 67 ct, a star spessartine from Nigeria, and the effect of chemical alteration on conch pearls.
Another impressive specimen was a 130-kg block of albite on which rested a 24 X 60-cm crystal of smoky quartz from the Navegadora mine, Conselheiro Pena, Minas Gerais, Brazil--a locality well known for its fine spessartine crystals.
Especially since World War II, the pegmatites of the state of Minas Gerais have yielded some of the world's finest specimens of topaz, chrysoberyl, euclase, elbaite, and beryl (in all of its colored varieties); phosphate-rich pegmatites of the same state have furnished the world's finest specimens of brazilianite, beryllonite, eosphorite, hydroxylherderite, amblygonite and more; complex pegmatites of other kinds have provided cassiterite, xenotime, monazite and several rare-earth species; Brazilian specimens of titanite, phenakite, fluorapatite, kyanite, scheelite, spessartine and bertrandite are among the world's very best.
In the older classifications they were considered typical sodalithic pegmatites, with characteristic dominance of albite over microcline, lepidolite over other micas, spessartine over almandine and elbaite over schorl.
The beautiful gemmy orange spessartine crystals from the Loliando area are quite widespread around the market (including matrix specimens).
Most recently, remarkable, partially gemmy, trapezohedral spessartine crystals of a bright mandarin-orange color, up to the size of baseballs, have been found about 35 km northeast of Loliondo, close to the Kenya border.
Auguste) and "Grossular from Mali" (Bill Dameron); following "Classic Garnets: Spessartine" (six authors) we find "Spessartine from Tongbei" (Bert Ottens).
Spessartine on Quartz Shigar Valley, Skardu, Pakistan 33/4" tall pictured Ikons, Classic and Contemporary Masterpieces, pg.