The Alpine area is home to some spectacular stones that are rare and distinctive, including Red Plume, Black Plume and Bouquet Agates. Rock hunters have come to this region for many years to find specimens of these beautiful gemstones, but most of the best hunting places are on private land.
The best opportunities for the public to see and acquire specimens of local rocks are at the annual Alpine Gem & Mineral Show and year-round at Ocotillo Enterprises in downtown Alpine.
If you are a real rockhound and are looking for a hunt there are 3 ranches hosting guided hunts by local experts. You can find all the details at https://www.facebook.com/groups/775245782823113/permalink/1837215916626089
Agate Basics
Agate is a hard, durable mineral made out of quartz (silicon dioxide). It occurs all around the world, in every color, and in many different types of patterns. It is as beautiful as it is versatile: Agate has been used in jewelry and other decorative objects throughout history.
Some of the agate patterns are recognized by name and associated with a particular location. This is the case in the Big Bend region, where Red Plume Agate, Bouquet Agate, Black Plume Agate, and Pom-Pom Agate are just a few of the varieties found.
Bouquet Agate – Photo by Steve Ivie / Rockhounding USA
The Big Bend Region of Texas encompasses both volcanic and sedimentary areas. In much of the Big Bend, the volcanic rock did not explode from erupting volcanos, but instead cooled below the surface of the earth. As the magma cooled, heavier elements like metals sank to the bottom of the magma, and the gasses in the magma rose to the top. Millions of these gas pockets were left unfilled when the magma cooled into basalt, allowing the gasses to escape. The agate primarily forms in these empty gas pockets through precipitation (where silica dissolved in water precipitates out and stays in the empty gas pocket, along with trace minerals that cause the colors and patterns). If there are large cracks in the volcanic basalt, agate can grow in there, as well.
The agate that forms in an empty gas pocket is stronger and more durable than the basalt in which it grew. Eventually, the basalt cracks and breaks into small pieces, eventually turning into soil. This process first exposes and then releases the agate contained within the basalt. When first exposed, the agate is usually in the shape of the gas pocket where it formed. An agate in this form is called a “nodule”. Agate nodules in the Big Bend can vary from the size of an English pea to the size of large watermelon. By the time it’s released, however, it may be broken into pieces which don’t resemble the shape of the original nodule at all.
Big Bend Agate
In addition to agate, there are other quartz gemstones that occur in the Big Bend. Jasper, chalcedony, and quartz crystals are three of the most collectible, but there’s also petrified wood, and flint and chert. Different publications define each of these categories differently, but the important thing to remember is that they are all hard, durable stones, suitable for use in jewelry and decorative objects.
Red Plume Agate – photo © Steve Ivie / Rockhounding USA
You can get some agate of your own by purchasing it, or by going on a rockhunting field trip and finding some yourself. You can purchase agate that is “rough” (just as it looked when it was found), cut into a slab, made into a cabochon gemstone, or set into a piece of jewelry.
Bouquet Agate – Photo by Brad Tanas
Alpine’s Gem Show
Alpine is host to an annual gem show on the third weekend in April, held at the Alpine Civic Center. This show runs Friday, Saturday and Sunday. Admission is free, and there are vendors from the Big Bend, from Mexico, and from the rest of the world offering you fascinating gems, mineral specimens, and jewelry.
The above text is © Teri Smith, 2016