Waco Gem and Mineral Club, Waco, Tx

17.6 Phantoms and Inclusions


17.6: Phantoms and Inclusions

We‘re all familiar with quartz crystals that appear clear through-and-though, like clean window glass. But sometimes when you look into a quartz crystal, you might see the clear or fuzzy outline of another quartz crystal! This crystal-within-a-crystal is referred to as a phantom. A phantom is created when crystal growth is interrupted and later resumes. It‘s similar to looking at the rings of a tree trunk, which record periods of active growth and dormancy. Essentially, when looking at a phantom, you‘re seeing a smaller, younger version of the bigger crystal you‘re holding.

Phantoms can be seen in almost any type of mineral that produces a transparent or translucent crystal, such as quartz, calcite, fluorite, or tourmaline. But the phantoms you see most commonly sold on the market are in quartz. With quartz, you may see nearly clear, almost indistinguishable phantoms from different growth phases. But many times, between growth phases, the crystal termination faces may be lightly etched or may collect gas or liquid bubbles. When that happens, the phantoms are a ghostly white. Other times, the termination faces may be lightly dusted by a coating of a different mineral, creating phantoms of different colors. Green phantoms are created by thin layers of chlorite, reddish-brown phantoms from iron minerals like hematite, and blue phantoms result from the mineral riebeckite.

Phantoms are found in many quartz crystal deposits. The Brazilian gemstone districts are especially famous for them. Arkansas has yielded its fair share of white phantoms, and Peterson Peak (or Hallelujah Junction) on the border between California and Nevada is famous for its smoky quartz phantoms. Crystals containing phantoms are also called 'shadow crystals', 'ghost crystals', or 'specter crystals'. While the names may sound like something from a spooky nightmare, the effects are like a beautiful dream!

In addition to phantoms, you occasionally see inclusions in quartz crystals or other mineral crystals. An inclusion may be any material—solid, liquid, or gaseous—found inside a mineral. I mentioned light dustings of chlorite that might form in a quartz phantom. Sometimes rather than just a light dusting, a larger mineral crystal will form and will then get engulfed in the growing quartz crystal. In my collection, I have quartz crystals containing tiny garnets and others containing tiny pyrite crystals. Clusters of needlelike rutile crystals frequently appear as inclusions in minerals like quartz or corundum. A variety of gypsum known as 'hourglass selenite' from Oklahoma is well known for inclusions of clay and sand in the form of an hourglass figure.

One really cool type of inclusion is when an air pocket forms within a crystal and contains a little drop of water. Tilt the crystal this way and that way, and you‘ll see the water droplet move up and down, as with a carpenter‘s level. Such a crystal is referred to as an enhydro.