The Exquisite Crystal Family
One of the most common minerals found in the continental crust of Earth, quartz finds its major chemical component in silicon dioxide (SiO2). Crystal, a member of the quartz family, refers to transparent crystalline quartz.
Crystal in general is colorless and transparent but tends to display different colors and special appearances when it contains various microelements or coexists with other materials, thereby leading to the birth of the crystal family” that houses several members endearing to collectors. For example, when containing a trace amount of ferric or manganese ions, it becomes purple crystal.
Sometimes, crystal coexists with other minerals. Certain crystals are called “grass quartzes” as they contain elongated needle-like crystalloid minerals in golden red resembling weeds growing inside the crystals. If the inclusions are green minerals like chlorite or epidote, they are commonly called “green phantom quartzes.” The black “smoke crystals,” on the other hand, are those containing a trace amount of a radioactive element like thorium (Th), which constantly releases radiation to damage the internal structure of the silicon dioxide in crystals, thus causing a flawed crystallization that impedes the penetration of light and blackens the otherwise transparent crystals.