from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A brownish to black mineral, chiefly (FeMg)2Al9Si4O23(OH), often having crossed intergrown crystals and sometimes used as a gem.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A dark brown nesosilicate mineral that has crystals that cross and intergrow
from the GNU version of the Collaborative International Dictionary of English
- n. A mineral of a brown to black color occurring in prismatic crystals, often twinned so as to form groups resembling a cross. It is a silicate of alumina and iron, and is generally found imbedded in mica schist. Called also granatite, and grenatite.
from The Century Dictionary and Cyclopedia
- n. A silicate of aluminium and iron occurring in reddish- to yellowish-brown or brownish-black prismatic crystals. These crystals are often twins, in the form of a cross, whence it is called cross-stone. Also staurotide, qrenatite.
The natural materials include the minerals staurolite, quartz, diamond and corundum.
In the metamorphosed Thunderhead Sandstone it was found that at the staurolite isograd, the boundary between the garnet and staurolite zones, the mineral chlorite disappears from the rocks and muscovite decreases sharply, whereas staurolite appears and biotite becomes more abundant.
As can be readily seen in figure 1, whereas seven of the samples averaged around 30 Po radiohalos each, the two samples straddling the staurolite isograd contained 177 and 147 Po radiohalos respectively.
However, where the mineral reaction around the staurolite isograd has produced a lot of hot water, large numbers of Po radiohalos have formed.
The thick Thunderhead Sandstone (Upper Precambrian Great Smoky Group) in the Great Smoky Mountains along the Tennessee/North Carolina border was deformed and regionally metamorphosed during formation of the Appalachian Highlands, beginning in the so-called Devonian (that is, early in the Flood year).12-14 With increasing temperatures and pressures from northwest to southeast, the regional metamorphism produced in these sandstone layers a series of chemically and mineralogically distinct zones of schists and gneisses.15 These zones are named according to the first appearance of the distinctive metamorphic minerals which characterize them as the intensity of the metamorphism increased laterally—the biotite, garnet, staurolite, and kyanite zones.
“It’s brown staurolite,” Sammy explains as he hands one to Reverend Love.