Citrine
When quartz is yellow, it is called citrine. It is one of the November birthstones and represents the 13th wedding anniversary. The majority of citrine on the market is either heat-treated smoky quartz or amethyst. Natural citrine is found in limited quantities. Citrine can form together in the same crystal as amethyst. The amalgam is called ametrine.
Where it's Found: Brazil, Spain, USA, Russia, France, Scotland, and Madagascar.
Mohs Hardness Scale: 7
Rutile Quartz
The defining characteristic of this quartz are its inclusions of needle-like crystals called "rutile." The rutile forms within the quartz and can be golden, silver, black, red, green, or mixed. By their nature, no two stones are the same.
Where it's Found: Around the world, including Brazil, Madagascar, India, Australia, and the US.
Mohs Hardness Scale: 7