Amblygonite Rough from Brasil
Amblygonite is a common fluorophosphate mineral found in pegmatite deposits. Though the mineral is common, transparent specimens that can be faceted are quite rare, so that makes it an interesting gemstone.
Amblygonite is usually white, cream or pale yellow in color, though it can also occur in green, blue, gray or pink. Since the light colored amblygonite often looks similar to other common host rock members it can easily be confused with minerals such as quartz and albite. But there are two features of amblygonite which are key to its identification.
Since amblygonite contains a significant amount of lithium in its composition, it can be identified with a flame test -- powdered amblygonite will produced a bright red flame when placed in a gas flame. The other distinctive feature of amblygonite is its cleavage. Cleavage is in four directions, but every cleavage plane has different qualities -- there is perfect cleavage in one direction, good cleavage in two others, and distinct cleavage in the fourth direction. In addition, all cleavage angles are non-right angles. In fact amblygonite draws its name from the Greek amblus, blunt, and gouia, angle, due to the obtuse angles of cleavage.
Amblygonite Rough from Brazil
Amblygonite was first discovered in Saxony by August Breithaupt (1791-1873) in 1817. Breithaupt was a German mineralogist who studied under Abraham Gottlob Werner at the Freiberg Mining Academy. Breithaupt became professor of mineralogy at Freiberg when Friedrich Mohs (inventor of the Mohs hardness scale) left that post to become professor at the University of Vienna. Breithaupt is credited with the discovery of 47 different mineral species.
Pale yellow faceted amblygonite can sometimes be confused with golden beryl, citrine and scapolite. However, amblygonite is softer than both beryl and citrine, with a hardness rating of 6 on the Mohs scale (similar to scapolite).
Gem quality amblygonite has been mined in Burma, Brazil, Sweden and the USA (California). There is also an unusual purple variety from Namibia. Amblygonite occurs in pegmatite deposits along with other lithium-bearing minerals such as apatite, spodumene, tourmaline and lepidolite.