Pages

Showing posts with label Chinese Writing STone. Show all posts
Showing posts with label Chinese Writing STone. Show all posts

Tuesday, October 6, 2009

Not so Common of the Feldspars !

The first Feldspar, seen below, is a very popular healy-feelie stone found in California with a close cousin from China. The stones from both locations have the same name. Now, contrary to very popular beliefs, it is not a black stone with Andalusite crystals embedded in it. That is how some web sellers offering this particular stone describes it. Wrong, wrong, wrong.

So the question becomes -- what kind of Feldspar is it? Like Unakite, this stone is a composite that features lightly-colored 'calligraphic-like' feldspar crystals called 'phenocrysts' enclosed by a dark matrix of Basalt called the groundmass. Since the helter-skelter arrangement of the crystals rightfully reminds one of Chinese calligraphy, this rock was named "Chinese Writing Stone" in 1980. How these Feldspar crystals got mis-identified as Andalusite in unknown.
.
.
The second Feldspar type stone was originally said to contain four types of Feldspars. In actuallity, only one of its constituent minerals – anorthoclase – is a Feldspar. The other three minerals are two amphiboles (riebeckite and arfvedsonite) and a pyroxene (aegirine).
.
Feldspar is a rather expansive group of stones having many members that could one day qualify for ornamental uses as an increasingly eco-minded public begins to discover and delight in the dirt-cheap (pun intended) glories of the earth’s crust. But our Nebula Stone, shown above, is more of a hanger-on than a full fledged membern of the Feldspar grouping, unlike the fully accepted Feldspar gemstones called Sunstone, Moonstone and Andesine or more lapidary type stones like Labradorite, Amazonite and Larvikite, to name a few.
.
Thanks to Colored Stone Magazine for info and pictures.
.
.