Crystal Terminology & Identification
Have you ever been confused what certain terminology means in crystals? Have you visited a crystal shop and been curious what exactly someone means when they describe a specific crystal? What is a flashy specimen? What is a crystal phantom?
Let’s explore some common descriptive words for crystals.
Banding
Banding is a discoloration in a stone that can be a result of the forming of the stone or by a change in chemical composition. Banding is, quite literally that, lines or bands that form along a crystal in a similar direction. Banding is often most noticeable when it has bold and contrasting banding (as commonly found in Agate or Malachite).
Chatoyancy
Chatoyancy is an optical illusion in crystals where parallel inclusions in the crystal reflect a ‘cat eye’ appearance.
Cleavage & Fracture
When crystals break, they can either split leaving a clean, flat face called a cleavage plane, or fracture leaving a more rough, uneven surface. Cleavage forms along the minerals weakest points, where as fractures occur when a mineral is equally strong in all directions eventually causing uneven breaks or fractures.
Druse / Drusy / Druzy
Druzy crystal (also called druse, drusy) is a cluster of small crystals. These druzy crystals are a mass aggregate of small crystals that form on the surface of another stone. Druzy are caused by varying factors such as pressure, temperature, and fluids.
Flash / Flashy
Light play within the stone, typically due to compact layers within the stone that refract when light hits the surface, making it shine or flash in hues of red, orange, yellow, pink, purple, blue and green.
Lustre
The lustre within a mineral is essentially the reflection of light. This is used to determine the identification of a mineral. Lustre is divided into two subcategories, metallic and nonmetallic (and then further subdivided). Although it sounds straightforward, determining lustre is difficult to do by a photograph alone as a single mineral can exhibit multiple lustres.
Phantom
“Ghost-like inclusion which shows a former growth stage or period of development of the crystal. [..] Additionally, crystals showing a sharp transition between two different colours or levels of opacity can produce the effect of a 'phantom' crystal suspended within a crystal.” (Mindat.org)
Veins
Veins or veining in stones is a common way crystal shops describe their specimens. Veins in stones are typically fractures that then receive deposits of other elements, creating sheets of crystallized minerals within a stone.
