Mineral or Rock??? A mineral can be defined as a naturally occurring inorganic solid that possesses an orderly internal structure and a definite chemical composition. Some people, like physicists, might be guilty of picking up a rock and calling it a mineral. The term "rock" is less specific, referring to any solid mass of mineral or mineral-like material. Common rocks are often made up of crystals of several kinds of minerals. Lutgens and Tarbuck give the following list of essential characteristics of a "mineral": 1. It must occur naturally. 2. It must be inorganic 3. It must be a solid 4. It must possess an orderly internal structure, that is, its atoms must be arranged in a definite pattern. 5. It must have a definite chemical composition that may vary within specified limits."

Emerald is the mineral beryl with substitution defects of Cr(3+) or V(3+) replacing Al(3+). Beryl has the chemical composition Be3Al2(SiO3)6 and is classified as a cyclosilicate. It is the principal ore for the element beryllium.

Tsavorite is a variety of the mineral garnet a calcium-aluminosilicate with the formula Ca 3 Al 2 Si 3 O 12. Crystal form is cubic. Trace amounts of vanadium or chromium provide the green color. It is often called the Rolls-Royce of greens at Cadillac prices. From a collectors perspective, tsavorite is 200 times more rare than emerald, it is cleaner, more brilliant and not oiled or treated in any way.

“Tourmaline: Nature's source of Negative Ions” Tourmaline is one of the naturally pyroelectric minerals. Pyroelectronic charge in minerals develops on the opposite faces of asymmetric crystals. Is that why it’s in my hairbrush??? Tourmaline is a large group of aluminosilicate minerals, with variable composition: (Ca,K,Na)(Al,Fe,Li,Mg,Mn) 3 (Al,Cr,Fe,V) 6 (BO 3 ) 3 (Si,Al,B) 6 O 18 (OH,F) 4 Elbaite is one of the forms found as pink and green colors, having the general formula Na(Li,Al) 3 Al 6 (BO 3 ) 3 Si 6 O18(OH) 4. It is a silicate with lithium content, a relatively rare element. Crystal forms are trigonal.

Polarized micrograph Peridot is the gem-quality form of the mineral Olivine. It has the chemical composition (Mg,Fe) 2 SiO 4, with Mg in greater quantities than Fe. The depth of green depends on how much iron is contained in the crystal structure, and varies from yellow-green to olive to brownish green. Peridot is also often referred to as "poor man's emerald". Olivine is a very abundant mineral, but gem-quality peridot is rather rare. Peridot crystals have been collected from some Pallasite meteorites

heat Fe (2+) in Td (SiO 4 ) sites Quartz - SiO 2 -simplest silicate mineral, piezoelectric, chiral! + Ti(3+)

Replace: -S with I -Zn with Hg (at vertices) -Zn with Cu (in middle) Replace: -S with I -Zn with Hg (at vertices) -Zn with Ag (in middle)