Chalk Turquoise: is a term used to describe a lower grade Turquoise that has been dyed and stabilized with hardeners to produce a material that's durable enough to use in jewelry with a pleasing turquoise color. It has the same phosphate composition as Turquoise, only with lower amounts of copper, aluminum and/or iron. It's the metal content that results in the green to blue turquoise color. More recently, the name "Chalk Turquoise" is being applied to Reconstituted Turquoise or dyed Magnesite (MgCO3). Chalk Turquoise has become a popular substitute for high-grade Turquoise that is becoming increasingly more expensive and rare. It can now be found in a variety of new and contemporary colors such as lime green, bright yellow, pink and lavender.. Magnesite: (also referred to as Chalk Turquoise White buffalo or Wild Horse Turquoise) is a magnesium carbonate mineral (MgCO3) similar in crystal structure as Calcite. Visually, it can be difficult to distinguish from Howlite, Dolomite or Marble. Magnesite in its natural form is typically an opaque white, but can also range in color from gray to tan and sometimes contain light to dark matrix. Because it is a relatively soft and porous stone, it takes well to color enhancements and stabilizers. Like Howlite, it is often dyed and treated with hardeners to simulate more expensive gemstones, such as Turquoise, and is remarkably close enough to be mistaken for the real thing.