Category: Riebeckite In Quartz

Riebeckite In Quartz, is not a well known mineral although most people have probably seen stones that at one time were composed of riebeckite crystals. The typically dark blue mineral was named after a famous eighteenth century German explorer and minerologist, Emil Riebeck. Riebeckite is an important mineral for two main reasons: one for when it is there and one for when it isn’t.

Secondly, crocidolite is often found pseudomorphed by Quartz  into an attractive ornamental stone. The stone is extremely popular as a semi-precious stone and is known by many trade names such as Tiger’s Eye, Hawk’s Eye, Falcon’s Eye, etc. A pseudomorph is an atom by atom replacement of one mineral for another, without significant destruction of the original mineral’s outward shape. The pseudomorphing of riebeckite’s asbestos fibers does two things; it preserves the beauty of the fibers and their lustrous light effects and it produces a much more durable stone that is now, thanks to the silicification, suitable for carving and jewelry. Blue tiger’s eye has preserved the original blue color of the riebeckite while the more common brown color is the result of some oxidation of the iron into Limonite inclusions. Although it is improper to refer to tiger’s eye as being a form of riebeckite because there is no riebeckite present in the stone, credit must be given to this mineral for the aid in producing this wonderfully beautiful ornamental stone.

Riebeckite In Quartz, The chemistry of riebeckite is odd in that it includes two different iron atoms. One is ferric (with a plus 3 charge) and one is ferrous (with a plus 2 charge). The ferrous iron occupies the same position as and substitutes with the plus 2 manganese because both ions are of nearly the same size. The formula is written the way it is to show the different iron ions.