Aquamarine is the green to blue-green

Aquamarine, heliodor, emerald,goshenite and morganite are allmembers of the beryl family.  Beryl is an important source of theelement beryllium , a metal with a variety of modern commercial uses, particularly in manufacturing metal alloys. Unlike emerald, aquamarine gems are often completely flawless. However,inclusions may include mica, hematiteand liquid-filled (often salt-water)' tubes.' The largest gem quality aquamarineon record was found in Brazil in 1910 andweighed 243 lbs. A thirteen-pound uncut piece resides in the American Museum of Natural History.  By one account, when Russia andAfghanistan were at war, Afghanis, locating a probable aquamarine deposit, would pitch a tent over the area, making it an inviting target for the Russians to bomb -- thereby eliminating days, if not weeks, of digging.

shades of green and blue aquamarine crystal Aquamarine is the green to blue-green to aqua variety of the mineral beryl (from the Greek berullos, meaning any "crystal"). It isdichroic, appearing with color and without when viewed from different angles. Most gem beryl comes from a very coarse-grained rock that geologists call pegmatite, a form of igneous rock consisting of extremely coarse granite resulting from the crystallization of magma rich in rare elements. Aquamarine is colored by trace amounts of iron that find their way into the crystal structure. However, the majority of gem aquamarines on the market today have been heat treated -- by heating them in an electric furnace to 842� F (450� C) -- to produce the popular sky blue, dark blue, and blue-green colors from less desirable yellow or pale stones. photo: garimpo talhado minea, brazil Brazil is a major supplier of aquamarines where they are mined around Teofilo Otoni in the western part of the state of Minas Gerais. Pakistan and Afghanistan also have significant deposits, but given the political contretemps between Pakistan and India, the recent years of war between Russia and Afghanistan, and the presence of al-Qaeda and the Taliban, mining activity has been sporadic, at best, and getting product out of the countries difficult. Russia mines aquamarine in several areas, most notably the Urals, Transbaikalia (east of Lake Baikal), and Siberia. Several African nations such as Nigeria and Madagascar mine the gem. In the US, Colorado and North Carolina have deposits.

Rutilated quartz

Rutilated quartz with very fine light colored rutile is called "angel hair."  Rutile derives its name from the Latinrutilus, meaning "red," in reference to the deep red color observed in some specimens when viewed by transmitted light. Although rutile is commonly reddish brown, it can also be yellowish, bluish, green or even violet.  Rutiles can be up to 10% iron.

golden threads but no silver needles... Rutilated quartz is a quartz with large inclusions of the mineral rutile, a titanium-rich material. Rutile forms in quartz as what appears to be glimmering gold and red threads or 'needles' arrayed in patterns inside the stone. Since every pattern of rutiles within the stone is unique, each piece of rutilated quartz is unique. carved rutilated quartz egg Until relatively recently, rutilated quartz was considered mainly an ornamental stone (fit for crystals and carving), but its unusual inclusions -- often seen as golden-colored (a phenomenon of refracted light) -- have made it an increasingly popular stone with jewelry designers and the public. Rutile itself is an interesting and important mineral. A significant source of titanium dioxide, the metal is used for high tech alloys because of its light weight, high strength and resistance to corrosion.

Bolivian beauty

The unusual color variation found inametrine is due to the presence of iron in different oxidation states within thecrystalline structure. Exactly how ametrine's bi-color comes about, geologically, is still not fully understood.  Ametrine is relatively inexpensive, given the fact there's only one commercial mine in the whole world. Although the it is the world's only ametrine mine, most of the Anahi mine's production is devoted to producing amethyst. To add some perspective on theinaccessibility of the mine: it takes 2 � hours to fly from Santa Cruz to the mine's landing strip -- or one can travel from Puerto Suarez (Bolivia) by boat up the Paraguay River to Lake Mandior�, a6 hour journey and then a 2 hour truck ride via a jungle trail.

bolivian beauty A bi-color stone -- and Bolivia's most spectacular export -- citrine makes up the yellow-orange part of ametrine and amethyst, the violet-purple part. Ametrine is formed when iron impurities in quartz are affected in different ways by heat. (An example of how this could happen is if one side of the crystal was facing a vent or other such heat source. Any change in pressure would affect the temperature forming the citrine and amethyst would begin to form instead.) the vast pantanal wetland of bolivia Located in the far eastern part of Bolivia, traditional land of the nomadic hunter-gatherer Ayoreo (pronounced "ai-o-reo"), the Anahi Mine is the major producer of high-quality ametrine in the world. The mine also produces anahite, as well as amethyst and citrine. In the midst of a nearly inaccessible rain forest zone -- near the famous Pantanal wetlands, an area that establishes the borderline between Bolivia and Brazil -- the mine is four hundred kilometers southeast of Santa Cruz and is reached primarily by bush plane. one anahi mine entrance photo: anahi mine Ametrine -- which initially appeared on the market as Bolivianite -- has only been available to consumers in any quantity since 1980 when the Anahi mine in Bolivia became operational. Before the discovery of the large deposit in Bolivia, ametrine was also known as amethyst-citrine quartz, trystine or golden amethyst.

Another name for common opal ispotch .

Another name for common opal ispotch . It's the orderliness of the silica spheres within the stone that separates precious opal from common opal.Precious opal is made up of tiny uniform spheres of transparent hard silica which fit together in an orderly three dimensional frame and sit in a "bath" of silica solution. But, incommon opal, the silica spheres are intoo much disarray to diffract light -- hence, no play-of-color. When there is color -- that is, bits with "play of color" mixed with potch, it'scalled -- duh -- "potch and color."

silica spheres of precious opal vs. potch Common opal is defined as lacking a "play of color" and includes a rather long list of stones, all of which lack opalescence, color or luster for the most part. "potch and color" Opaque or glassy in a wide range or colors, common opal can be sometimes have a waxy luster, and is often fluorescent. It may be colored or contain dendritic (moss-like) inclusions. There are many different common opals, including: Hyalite is a transparent, colorless-to-bluish opal which forms in cavities in volcanic rocks. Hydrophane is a porous, opaque, light-colored opal which becomes transparent when soaked in water. Lemon (yellow) opal often has green-gold tones, small black and red-orange streaks, and a waxy luster. Moss opal contains dendritic mineral inclusions, resembling ferns or moss. Peruvian opal comes in shades of turquoise, aqua, and pale blue. Pink opal is sometimes sold as pink silica and contains black inclusions and dendrites. Prase opal is bright green, due to the presence of nickel. Wood opal is a replacement of wood by non-precious opal, often retaining the grained appearance and bark texture.

Alluvial amethyst

alluvial amethyst Amethyst is dichroic, showing a bluish or reddish purple tinge when viewed from different angles. Much amethyst that is mined is heat-treated to change the color to yellow -- which explains much of the citrine on the market today, natural citrine being somewhat rare. amethyst mine, brazil photo:silvestre garimpo One of the world's major producers of natural amethyst is the Anahi Mine in Bolivia (which also produces ametrine). The mine is located in the midst of the rain forest zone near the Pantanal wetlands, which establishes the borderline between Bolivia and Brazil. Accessible primarily by bush plane, the mine is four hundred kilometers east and slightly south of Santa Cruz, Bolivia. In Brazil and Uruguay, amethyst is often found in alluvial deposits in the beds or former beds of rivers where miners use the techniques of placer mining. (Alluvial gems often have quite a high specific gravity [density] compared to other minerals so that they are easily trapped in depressions in stream beds. This causes them to become concentrated, making them easier to mine.)

Geodes are a variable phenomenonand, therefore, many theories exist toexplain how they are created. The term geode is derived from the Greek word geoides which means "earthlike."  Some geodes are completely filledwith small compact crystal formationssuch as agate, jasper or chalcedony and are called nodules. The only differencebetween a geode and a nodule is that a geode has a hollow cavity, and a nodule is solid.  Volcanic lavas such as basalts may have round or almond shaped gas holes, partially or completely filled withcalcite, chalcedony, agate, crystallized colorless or amethyst quartz or other minerals. Many easily accessible geode collecting sites exist in the western US -- including California, Arizona, Utah andNevada. The state of Iowa is also hasgeodes: in fact, they are so prevalent thegeode is Iowa's state rock. A relatively cheap stone because it is aquartz, amethyst is found throughout the world. Were amethyst not so plentiful it would be much more expensive, given its beautiful range of purple shades, ranging from deep purple to lilac to mauve to purplish reds. If, after creating citrine from amethyst, one decides amethyst would be more desirable, the pseudo-citrine can bechanged back to the original amethystcolor by subjecting it to X-ray radiation. Methods of accessing alluvial gem gravels include open pits, shafts and tunnels, and dredging.

geodes: the variable phenomenon One of the amethyst forms with which the public is most familiar is the geode, split into two halves. what is a geode? amethyst geode Geodes are hollow, crystal-lined globular rock cavities lined with crystals that are found in sedimentary rocks like limestone (calcium carbonate) and dolomite (calcium magnesium carbonate) or in volcanic rocks. how are geodes created?Beginning as bubbles in volcanic rock or as animal burrows, balls of mud or tree roots in sedimentary rock, over a period of millions of years the outer layers of silica cool and harden while at the same time water containing dissolved silica begins to seep into the lava cracks or cavities. Eventually, the deposited silica minerals create crystals, most of which point towards the center of the cavity. Each geode is unique -- its secrets can only be discovered by cracking it open or dissecting it with a rock saw. The size and formation of crystals and their different shades of color is what makes each geode special, as a geode's rough exterior gives no indication of the often breath-taking secrets held within. For those who collect geodes, the anticipation of finding out what's inside never fades.