Yes They are Natural...Mostly

Merriam-Webster defines a geode as "a nodule of stone having a cavity lined with crystals or mineral matter". In the mountains of Brazil and Uruguay have formed, sometimes enormous, "log geodes".  Rather than the roundish shape normally associated with "nodules", these form as tubes within lava-type rocks...usually Basalt.

The most popular of the log geodes must be those containing crystals of Amethyst. This purple variety of quartz varies from pale lilac color to intense purple, and has been known since ancient times.  It gets its name from Greece, where ancient mythology held that Amethyst would prevent a person from becoming drunk.

Due to the very hard matrix (aka host) rock in which they form, heavy equipment and hard-rock mining techniques are utilized to recover these specimens.  When all goes well, they are able to remove the geodes intact, and then apply their artistic talents.  Arguably the most popular form is the "Amethyst Cathedral".  In this presentation, the log geode is cleaned of excess matrix and cut length-wise.  Frequently, it it necessary to use concrete or cement to build a flat base upon-which the specimen may sit solidly.  Sometimes, cement or grout is applied to the outside of the specimen to strengthen the piece, and paint is applied to provide a uniform appearance to the exterior.  So, while the Amethyst occurs naturally in geode form, some artistic license is used to deliver the best presentation.

Prevailing scientific opinion seems to hold that Amethyst is purple for two reasons (1) the presence of tiny amounts of iron in the Quartz, and (2) having been subjected to some kind of natural radiation.  The color can be changed to yellow (Citrine) or green (green Amethyst) by application of heat.  And, prolonged exposure to sunlight will cause the purple to slowly fade in intensity.

We try to keep several Amethyst Cathedral specimens on-hand at Crystal Moon Gallery, and most are visible on our website.  Please let us know if we can help you with some of these decorator specimens.

Considering Enhanced Gemstones...

Among the oldest of professions must be the fraudster.  Since humankind first began assigning value to objects, there seem to have been people seeking to take-advantage of that perceived value.  Around the same time must have begun the "poor man's" alternatives.  Items that cost a lot less, but look almost-as-good as items with socialized value.

Here at Crystal Moon Gallery, we believe in sharing as much information as we can, in an attempt to educate consumers, and help avoid any unpleasant surprises.  This posting is an attempt to share information on commonly-encountered terms and actions that may not be perceived as entirely honest.

"Lab Created" - Most gemstones can now be created in a laboratory to almost any specification of color, purity, and perfection.  There is a long history of laboratory created gems and minerals (remember the alchemists trying to create gold?).  And, while we do not intend to imply any ethical issues with the creation of these stones, we do feel they should be accurately identified as such.  Amusingly, the ubiquitous stone of the lapidary hobby, Agate, has never been successfully created in a lab environment.

"Naturally Formed" - Our term for stones that were formed in the earth and mined from the ground.  Such stones may have subsequently undergone additional processes to increase their desirably.  Such processes are sometimes not disclosed to subsequent purchasers, but we offer educated guesses to our patrons.

"Heat Treating" - Some gemstones, especially Rubies and Sapphires are subjected to high heat to improve color and eliminate inclusions.  This is a process common in the gemstone trade, and certain stones should probably be assumed to have been heated.  These would include Citrine, Tanzanite, Red Tiger-Eye, Zircon, as well as the previously mentioned Ruby and Sapphire.

"Glass Filled" - High-quality rubies have always been rare and expensive.  In recent years, it was discovered that Lead-Glass (e.g. stem-ware) has a refractive index comparable to ruby.  And, at high-heat and under pressure or vacuum, molten glass will fill cracks and inclusions in less-than-perfect rubies.  Highly transparent rubies should probably be assumed to be glass-filled.

"Irradiated" - Exposing stones to radiation is essential to providing those rich blue Topaz stones...natural blue Topaz is very lightly colored.  Radiation is also used on Quartz (to create smokey quartz...aka "smokey topaz").  Other stones sometimes irradiated include Diamond, Tourmaline, and Zircon.

"Stabilized" - porous stones are placed in a liquid polymer, and either placed under pressure, or a vacuum to draw the polymer into the stone.  A very common practice with Turquoise to prevent color-change over time, as well as improve lower quality stones.

"Reconstituted" - Dust and chips from some stones are combined with polymers or resins with heat and/or pressure to create blocks of (generally) uniformly colored stone.  Turquoise and Amber are frequently reconstituted.

Many stone enhancements are difficult to recognize in the finished product.  And, most retailers do not have the equipment or expertise to run all necessary tests on stones.  Our opinion?  If you are buying a stone for the purpose of an 'investment", request GIA certification.  If not...assume the stone is enhanced, and make your purchase decision based upon whether you will enjoy owning it.

Gypsum, Selenite, Alabaster and 'rose rocks'

The mineral Gypsum has many different forms, and many commercial uses.  Essentially, Gypsum is a sulfate of Calcium...bonded with water.  Commercially, Gypsum is ground into powder and heated to drive-out much of the moisture.  Then, it can be made into wall-board, chalk, plaster-of-paris, or as a component in myriad other compounds.  In all of its forms, it is water-soluble.  That is to say, it can dissolve in water.  We've heard stories of Alabaster or Selenite being used in aquariums and fountains...and they lead to unhappy endings.

The massive, generally fine-grained form of Gypsum is known as Alabaster.  And, due to impurities, may be almost any color from white to near-black.  It is a soft mineral, and can be readily carved with hand-tools.  In the area around Cap Rock Canyon in the Texas panhandle, one can see periodic outcroppings of alabaster.  From the road, it stands-out as white against the red sand/dirt.  In addition to the water in its molecular structure, Alabaster will absorb water from the surrounding soil.  So, should you find alabaster in the field, it is recommended to allow the rock to dry in an controlled environment.  Otherwise, it can develop cracks.  Also, one can tell if the Alabaster has been exposed very long by closely examining the surface.  Frequently, one will find tiny traces of water erosion.  Common wisdom holds that 'fresh' Gypsum is better for carving than 'sugary' (once you see alabaster with water erosion, this term will make sense).

Satin Spar is another form of Gypsum found in the panhandle of Texas.  This Gypsum is fibrous, and forms in more-or-less horizontal seams, with the fibers running vertically.  Colorless Satin Spar, makes fascinating spheres.  When looking through the ends of the fibers, one can seen an image of an object on the other side of the sphere.  When looking 'across' the fibers, spheres can show a stunning "cat's eye" effect.  Thinner pieces of Satin Spar, when saturated with water, can become quite flexible (and fragile).  Then, when dry, return to their familiar rigid rock-like character.

Crystallized Gypsum is generally called Selenite.  Some of the largest individual crystals in the world are Gypsum crystals located in Mexico.  Gypsum can crystallize very quickly, as seen in the Great Salt Plains National Wildlife Refuge.  This location is famous for "hour glass" crystals that have sand or mud inclusions that frequently resemble an hourglass.  And, crystals grow so quickly that managers are able to rotate the collecting area to a different grid area every year or so to assure availability of fresh crystals.  We are unable to offer any of these crystals for sale, as collection is limited to personal use. 

Selenite may also crystallize in clusters that can resemble flowers.  The shape is the result of inter-growth of thin bladed crystals.  These occur in multiple locations around the world, and are known variously as Desert Rose, Gypsum Rose, Selenite Rose, etc.  Colors vary, depending upon whether inclusions (frequently sand) are present.  We have several varieties of Gypsum at Crystal Moon Gallery, and enjoy talking about this fascinating mineral.