Be 3 Al 2 (SiO 3) 6, used in all forms of jewelry, and less transparent stones are cut into cabochons.
On the Mohs scale of hardness Emeralds can range from a 7.5 to an 8. The emerald s green color is caused by the presence of chromium and iron. Emerald is a variety of green beryl whose chemical formula is Al2Be3Si6O18. Most of the world s emeralds are found in Columbia, Brazil, and Zambia. Emeralds often contain inclusions and other flaws. These flaws however are not considered negative aspects but that they contribute the gemstone s character. Beryl, the mineral of which emerald is a variety, has a chemical composition of Be 3 Al 2 (SiO 3) 6. When pure, beryl is colorless and known as goshenite.. Trace amounts of chromium or vanadium in the mineral cause it to develop a green color. USES. Emerald is one of the most valuable gemstones. It is the most famous green gemstone, and its deep emerald-green color gives it its unique status. It is used in all forms of jewelry, and less transparent stones are cut into cabochons. Good quality Emerald specimens are highly valued by collectors. Emerald has the chemical composition Be 3 Al 2 (SiO 3) 6 and is classified as a cyclosilicate. It has a hexagonal crystal system 6/m2/m2/m. Its density is 2.67-2.78 and it has an index of refraction in the range 1.566 to 1.602. Emerald is neither molecular or has an exact formula. It is beryl mineral with chromium and perhaps vanadium that give color. Beryl has complex structure with a formula Be3A … l2(SiO3)2 which is best described as containing a beryllium-silicon network ion balanced by Al3+. The replacement of Al3+ by Cr3+ up to 30 % by weight gives the color. (CR£+ is transition metal ion with d electrons that can be excite by light.
http://skywalker.cochise.edu/wellerr/students/emeralds-ashley/emeralds.htm http://geology.com/gemstones/emerald/ http://www.minerals.net/mineral/emerald.aspx http://hyperphysics.phy-astr.gsu.edu/hbase/Minerals/emerald.html http://www.answers.com/Q/What_is_the_Chemical_Formula_for_Emerald
what is the chemical formula for emerald and what is it used for