All About Quartz!
While the Earth's crust amounts to less than 3% of our planet's total volume, silicate minerals account for more than 90% of it. At its very basic; what we know as "quartz" is the crystalline form of silicone dioxide and is a type of silicate mineral.
Etymologically, "quartz” is derived from the German word “quarz” and Ancient Greek word for ice, "krustallos", which reflected the belief that quartz was permanently frozen water as Roman naturalist Pliny the Elder suggested. Cultures throughout the world use quartz as talisman for ritual signifying everything from ownership (Romans) and to prevent aging (Egyptians). One thing is for sure, humans have enjoyed quartz crystals for millenniums.
Quartz Forms in One of Two Ways.
The first is in igneous rock, quartz forms as magma cools. You can think of silicone dioxide crystallizing as it cools the same way water turns into ice. The second option is from geothermal waters as silicon dioxide dissolves in pressurized, hot water. When the pressure drops, the silica-rich water saturates and quartz forms. Imagine how sugar dissolves in tea.
But Have You Ever Wondered How It Gets Its Unique Coloring?
Rose Quartz gets its distinctive pink hue from impurities of titanium, iron and manganese present during formation.
Amethyst is purple because of missing electrons in the crystals and iron impurities. Citrine is yellow, also from iron impurities. Smoky Quartz is darkened by the combination of missing electrons and aluminum impurities.
"Chalcedony" is the generic name for microcrystalline quartz which includes agates (banded and semi translucent) and jaspers (opaque). Blue Chalcedony gets its beautiful milky light hue from
impurities of copper, manganese, titanium, and iron.
Natural Citrine is typically light golden with brown or smoky hues. The bright yellow-orange quartz that is sold as Citrine is commonly Amethyst that has undergone heat treatment (usually called "heated amethyst"). This doesn't make the crystal any less precious. In fact, heat treatment is considered a natural type of enhancement.
Both Citrine and Amethyst naturally gained their coloring from iron impurities and the heat treatment is essentially a continuation of what first occurred underground. During the process, stones are reheated upwards of 1600C which causes inclusions, like iron, to reform and permanently change the color of the crystal.
How to Spot Heat-Treated Citrine:
Here's a quick tip: you can spot a heated citrine by looking at its color and price.
Heated citrine is a usually a bright yellow-orange color or dark brown. It is also far more affordable. Natural Citrine is quite rare and comes from Russia, France and Madagascar. Its price is therefore more costly than the ever-abundant amethyst-heated citrine.