Morganite, beryl

Beryl. Beryl [1302-52-9] Be Al Si O g, is called aquamarine [1327-51 -1] when pale green or blue from inclusion of Fe emerald [12415-33-7] when dark green from Cr or at times V, and morganite or red beryl when pink or red, respectively, from Mn. Only the synthetic emerald is in commercial production, although the other colors can also be grown. Both the flux and hydrothermal techniques are used to grow this luxury synthetic. 

A colorless mineral known as corundum (composed of aluminum oxide) is colorless. A red variety of corundum known as ruby, a precious stone, owes its color to impurities of chromium within the crystal structure of corundum. Blue and violet varieties of corundum are classified as sapphires, the blue being the result of iron and titanium impurities, and the violet of vanadium impurities within the corundum crystal structure. Another colorless mineral is beryl (composed of beryllium aluminum silicate) but blue aquamarine, green emerald, and pink morganite, are precious varieties of beryl including different impurities aquamarine includes iron, emerald chromium and vanadium, and morganite manganese. 

Mineral gemstones that have the same basic chemical composition, that is, are composed of the same major elements and differ only in color, are considered as variations of the same mineral species. As gemstones, however, minerals that have the same composition and crystalline structure but exhibit different colors are classified as different gemstones. Beryl, for example, a mineral (composed of beryllium aluminum silicate), includes a pink variety, known by the gemstone name of morganite, and also a well-known green variety, emerald. Table 18 lists and classifies, by composition and color, gemstones that have been appreciated since antiquity. 

The radio-luminescence of transition metal doped natural beryl has been studied (Chithambo et al. 1995). It was found that Mn containing samples gave intense red radio-luminescence with sharp emission lines, while the Mn activated beryl (morganite) emission is more than twice as bright as that from emerald. Such luminescence has been ascribed to Mn ", but it may be supposed that such emission is connected with Mn luminescence. The laser-induced time-resolved luminescence spectra of natural morganite revealed a band peaking at 730 nm, which may be preliminary ascribed to the Mn center (Fig. 4.52). 

In optical spectra of emerald (Neuhaus, 1960 Poole, 1964 Wood and Nassau, 1968 Schmetzer and Bank, 1981), Cr3+ CF bands are located near 16,130 cm-1 and 23,530 cm-1 and are assigned to cations in octahedral sites. Similar bands for octahedral V3+ ions in beryl occur around at 16,000 cm-1 and 23,800 cm-1 (Beckwith and Troup, 1973 Schmetzer, 1982 Ghent and Lucchesi, 1987). Spectral features of pink and red beryls in the region 18,000-20,000 cm-1 (Wood and Nassau, 1968) may originate from crystal field transitions in Mn3+ ions in morganite. 

Morganite (rose beryl) Pink Mn (also in red beryl)... 

Description. Morganite is a pink to peach-colored gem variety of beryl, named after J.P. Morgan, the famous financier and banker. The color is due to the doping by manganous cations. A deep red gem variety of beryl occurring at the Ruby Violet Mine in the Wah Wah mountains Utah, is not called morganite, but red beryl. Heat treatment of some specimens renders them colorless, in others heating may be used to drive off a yellow overtone produced by a yellow color center to yield a nice pink. 

Varieties of minerals are a subdivision of species and their names are not recommended by the IMA and are not constrained by this international body. Varieties are principally used by gemmologists and commercial enterprises. In many cases, the criteria for distinction include color (e.g., ruby and sapphire are varieties of the species corundum emerald, aquamarine, heliodor and morganite are varieties of the species beryl). No mineral species has as many different variety names as does a-quartz (agate, amethyst, chalcedony, chrysoprase, citrine, cornelian, and many more). 

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