Since Mariposite is from Mariposa, CA, shouldn't Chinese writing rock come from China?
But Chrysanthemum stone does come from China!
Both stones, primarily limestone with with andalusite crystals are rightly called Porphory (igneous rocks that have phenocrysts - large crystals or grains). The limestone is usually dark gray with a slight greenish undertone. The crystals can be close to the color of the limestone. The ones that make for the best contrast for lapidary are white or clear; giving good contrast.
|Cab I made with Chinese Writing rock|
Chinese writing rocks were first found and described in the 1960's when it was uncovered during road construction in the Sierra Nevada foothills near Auburn, CA. People who saw it thought the random crystal structure imbedded in the base rock resembled characters from Chinese writing, and they really do.
The slab I made this cab from is stained with another mineral. Iron?
|Chinese Writing Rock I found in river rocks|
This is a Chinese writing rock I found in a bunch of river rock. It has the normal green tones. I keep this one on my desk because I think of it more as a thinking rock, trying to figure out what the shapes might be.
|High Quality Chrysanthemum stone Bing Image|
Chrysanthemum stone, on the other hand, is found in the Hunan Province's Yangtze River Valley in China. Aside from the geography, the characteristic that divides them is that the dandalusite crystals in the Chinese writing rocks are exceedingly random, the ones in the Chrysanthemum stone are centered with the crystals spraying out in a floral pattern resembling the chrysanthemum flower.
|Chrysanthemum stone/yard rock|
This, on the other hand, is poor quality Chrysanthemum stone. You can see the flower formations, but they are unclear and unfinished. I got this one at an estate sale for a former rock hound.
IN MY SHOP
My club shop has been closed for a while because of Covid-19, so even if I wanted to harvest a slice off my not-terribly-good-quality Chrysanthemum yard rock, my 10" rock saw couldn't handle it. So my comments will be based on some Chinese writing rock I've managed to acquire.
The Mohs hardness of the stone can range from 5-7, which will have a significant impact on how well it polishes.I've seen other lapidaries do marvelous things with it, but I don't get a lot of satisfaction from the little I've done, like the cab at the top (which I had to use spray sealer to give it a polish--it just looked dead).
So while I love looking at them, neither Chinese writing rock nor Chrysanthemum stone are items I search out. In fact, if I had a piece like the high quality Chrysanthemum stone above, I'd keep it as a specimen. It's beautiful!
Until next time,
Your Lapidary Whisperer,