Thursday, October 31, 2013

About Agates

Agates are some of the most creatively striped gemstones found in nature. Agates are found in all colors of the rainbow, with blue and green being the most unusual. Agates are a form of chalcedony (kal-sed'-nee) quartz, they are classically associated with volcanic rock. They differ from jasper in the fact that agates are composed of fibers of crystalline quartz, while jaspers are composed of grains of crystalline quartz. (Jasper will be the subject of another blog post.) Agate hardness on the Moh scale varies between 7 and 9.
Agates are formed when gas bubbles that are trapped in solidifying lava become filled with alkali and silica-bearing waters and other mineral impurities, which then gel. The alkali attracts the iron in lava, and the bands of iron hydroxide are created in the gel. Over time, the gel loses water and crystallizes, leaving the bands intact. This is why agate is often found with rings like a tree trunk. It can have tiny quartz crystals, called drusy or druzy, form within that will add sparkle and uniqueness to the stone. Drusy is sometimes cut from the stone and used by itself.
Agates are found all over the world, including Africa, Asia, Brazil, India, Italy, Mexico and the USA. Agates are usually named for the place they are found, but there are different types of banded formations that are added to their name. Listed below are some of the formation types.
Fortification agate- in this type of agate, bands crystallized into concentric layers that basically followed the shape of the cavity it formed in. When sliced, the bands resemble the aerial view of a fort.
Water line agate or onyx- in this agate formation, gravity controlled the formation of the bands. The solution either entered the cavity slowly, allowing for one band to form at a time, or it drained out slowly. The bands in these agates are almost perfectly parallel.
Shadow agate- these agates are formed with alternating translucent and opaque bands. The shadow effect occurs when light moving across the surface causes what appears to be movement across the face of the stone.

Eye agate-this unusual characteristic forms when most of the silica drains from the cavity, leaving behind only droplets that bead up on the inner wall of the cavity. Sometimes crystal growth will continue from this drop similar to the formation of stalactites in caves. Later, the cavity fills in with the usual deposits of chalcedony micro crystals.

Plume agate- these agates first had formations on the outside layer that formed before the deposit of the chalcedony bands. They are filament growths of mineral inclusions that look like feathers or ferns.
Moss agate-this type of agate has mineral inclusions that look like landscapes, plants or trees. These inclusions usually consist of iron or manganese oxide. Sometimes the inclusions inhibit the chalcedony banding and let the mineral clusters freely grow in the silica gel.
Seam agate- these agates grow in cracks in the host rock, rather than in cavities. The bands form in parallel rows that follow and fill in the crack or the seam.

Somewhat in a class by themselves are Lake Superior agates. These agates are only found in a certain region of the US. Glacial activity spread the agates throughout Minnesota, the Upper Peninsula of Michigan, and extreme Northwestern Wisconsin. They can also be found around the Thunder Bay in
NW Ontario, Canada. Lake Superior agates are known for the rich orange, red and yellow coloring. This comes from the iron that is leached from rocks formed millions of years ago from iron rich lava.

Agates are said to be very powerful gemstones. The healing and metaphysical properties are as varied as the colors of the agates themselves.

Bamboo Agate-
 Blue Lace Agate
 Translucency of Blue Lace Agate
Dyed blue agate slice with druzy

Plume agate-photo courtesy of Stones That Rock

Saturday, September 28, 2013

Morganite is the featured gemstone

The lovely pink gemstone, Morganite, is in the beryl family, which makes it a cousin to emeralds and aquamarines. Discovered in 1910, on an island off the coast of Madagascar, Morganite was named for legendary financier and gem collector, J.P. Morgan, after being called simply pink beryl for the first year or so it was around. Morganite is the official name of this beryl, but there has been some attempt in the jewelry trade to change the name to pink emerald, to make it sound more valuable. Morganite can also be found in colors from peachy pink, violet pink or a light lilac, and a light salmon color.

On the Moh scale, Morganite has a good hardness of 7.5 to 8. Unlike emeralds, which often have inclusions, Morganite is usually quite clean and clear. Heat treating is the most common way to bring out the pink in this gemstone. It also removes any yellow shading that might be in the stone.

Most Morganite today, comes from Pala, California, but is also found in Afghanistan, Brazil, Madagascar, Mozambique, Namibia, and Zimbabwe. It is also found in Maine, in the U.S.. In October of 1989, the Rose of Maine, was found at the Buckfield Quarry in Buckfield, Maine. This stone was somewhat orange in hue, and measured 9 inches (23 cm.) long, and about 12 inches (30 cm.) across.
Along with the matrix, it weighed just over 50 lbs. (23 kg.).

Morganite is valued first and foremost for the intensity and saturation of color, followed by size and clarity. The beautiful rosy hues are most often found in larger stones. Pink is the most popular color for jewelry, but the unheated peach and salmon stones have found popularity among collectors. Rare, magenta colored Morganite from the original deposit in Madagascar is still considered to be the finest and the rarest variety of this gemstone.

It is believed that Morganite can foster love, tolerance and empathy, acceptance, and a live and let live attitude.

The Rose of Maine.
 If you want to see more of this beautiful gemstone, just go to google images and put morganite in. You will find some gorgeous rough and polished samples.

Tuesday, September 17, 2013

Tanzanite is the featured gemstone

This beautiful blue lavender gemstone is relatively new on the gemstone market. It was discovered in 1967 by a tailor who was looking for rubies and was led to a deposit of blue stones, in the foothills of Mt. Kilimanjaro, by a group of Masai tribesman. It was first called Blue Zoisite, because it is a type of zoisite, but was later renamed Tanzanite by Tiffany a&Co. who wanted to capitalize on the rarity of the stone which is only found in Tanzania. Several claims were filed, which led to many mines being opened. In 1971, the Tanzanian government took control of the mines, and in 1976 turned the running of the mines over to the State Mining Corporation. Their methods caused production to drop. Tiffany stopped promoting and buying the stone in the late 70's due to the unreliability of the supply. By the late 80's, the government had lost control of the area and it was flooded with thousands of illegal miners. By 1991, the government had regained control of the area and began issuing licenses to private domestic parties, which has helped increase and stabilize the supply. However, when these mines are played out, the only Tanzanite available will be what is already on the market. Expert geologists maintain that the odds of Tanzanite being found anywhere else are one in a million.
The most prized color for Tanzanite is either the sapphire blue or the very intense violet blue. Most Tanzanite mined today is a brownish color, which is heat treated to bring out the deep blues and purples in the stones. Since heat treatment has no effect on the price, it is assumed that finished gems (cut and polished) are heat treated. Any treatment should be disclosed by the seller. On the Moh scale, it has a hardness of 6.5.
There are several gemstones that are confused with tanzanite, among those are iolite, blue spinel, and lower quality blue sapphire. There is a lab created tanzanite called Tanzanique. It does not display the same light defraction as natural tanzanite.
In October, 2002, the American Gem Trade Association, added Tanzanite as a birthstone for the month of December, along with Turquoise and Blue Zircon.
It is believed that Tanzanite can be used to enhance psychic abilities, composure, harmony and poise. It is also said to be beneficial for lowering stress levels and blood pressure and in getting people to slow down and take it easy. It is sometimes called the workaholics stone.
These are a couple of the tanzanite stones I have.