Sunday, August 22, 2010

GEMSTONES - Texas Favorites !

West Texas is famous for its wide variety of unique and beautiful Agates and Jaspers. Some types are highly prized by collectors all around the world. 35 million years ago, volcanic activity in the Big Bend area produced the environment for these beautiful gemstones. Quartz crystallizing as nodules inside gas pockets, or in cracks to form vein type agate, delicate plumes, bands, moss or bouquet patterns of different colors are actually crystals of impurities such as iron oxide, other oxides, hematite, etc. Agates and Calcedony are widespread throughout this region, but only a small amount it is of lapidary interest. Agate has been found south of Sierra Blanca, all the way down the Rio Grande, past Del Rio. Texas has no public lands to collect on, so there is still a lot to explore, if permission can be obtained from the ranchers. Just remember, don't go past a fence line without a ranchers permission, you might regret it !
One of the most famous is Red Plume Agate made famous by the Woodward Ranch. The ranch, located south of Alpine, offers Agate collecting for a fee. There are also trips out of Alpine to the Walker ranch for a daily fee. Although Red Plume is found only on the Woodward Ranch, there are several other types of Agates to be found on the Woodward Ranch, as well on other ranches in the Alpine and Marfa areas. Black and Brown Plume Agate are the most common lapidary grade. Banded Agate is also fairly common and near Alpine it is usually white, nearly clear, but can be shades of red, purple or pink, often surrounding a plume. Yellow Plume Agate can be found in the area but is difficult to cut. There is a type of Orbicular Agate found south of Alpine called Peanut Agate which can be quite beautiful. Most of the lapidary grade Agate found south of Alpine is found in biscuit shaped nodules with a dark red skin.
Marfa Texas has some of the most beautiful Bouquet Agate in the world that come in pastel colors in "bouquet" patterns and are the most sought after by collectors. The bouquet pattern can be found with black plume in both white skin and black skin Agate. A lot of this Agate is egg shell, thin coating of Agate lining the gas pocket, often with the botryoidal crystals. This usually is a good sign of quality plumes or bouquet. Black skin egg shell typically is black or blue and white banding. Balmorael Agate is famous for its blue color, banded often with black plumes. The skin is usually black with a white patina on the surface. It appears to be fairly wide spread in isolated pockets northwest of the Davis Mountains.
Topaz, the state gem of Texas, is found within the borders of the state only in Mason County. It occurs in granite outcroppings principally in the Streeter, Grit, and Katemcy areas. It is usually found in streambeds and ravines but occasionally can be located atop the ground. Topaz resembles quartz and ranges in color from clear to brown to yellow to sky blue. The blue stones are especially beautiful and extremely rare, and most interesting when faceted in the Lone Star cut.
Llanite is a hypabyssally intruded Rhyolite with phenocrysts of microcline and euhedral Quartz. The quartz crystals are blue hexagonal bipyramids. The unusual blue coloration of the Quartz is thought to be due to ilmenite inclusions. This gemstone is named after Llano County, the only place in the world where Llanite is found. A dike of Llanite outcrops in the Texas Hill Country north of the town of Llano. Rough, especially older material will have a definite reddish cast, but newer finds and finished and polished stones tend more towards the gray tones, but the blue Quartz stands out no matter when dug. Then in the Marble Falls and Burnett areas one can find all kinds of Granite and Marble. These are primarily used for counter tops and building construction.
We have just barely scratched the surface of the various unique as well as common gemstones and rocks that can be found within the State of Texas. Several books are available and many sites can be Googled on the Internet to obtain the names of the ranches that allow rock collecting as well as groups and persons who will act as guides. In winter, be prepared for a cold and wet trek, in summer a scortching hot, dusty and windy trek. Just remember, many great finds have been made along the highways cuts and grades as one drives this very large and diverse State. Here is a short list of what can be found in Texas:::
[number in ( ) is identified specific varieties]
AGATE (some 17+)
CHALCEDONY (some 9+)
FELDSPAR (some 4+)
GARNETS (some 6+)
GEODES (unknown number)
GRANITE (some 26+)
JASPERS (some 21+)
MARBLE (some 14+)
QUARTZ (some 8+)
RHYOLITE (some 3+)
TOPAZ (some 7+)