to 
iS) 
Phosphate Rocks of South Carolina, 
” 
The “ Buhrstone” takes its name from a similar 
rock formation, of the same age, extensively quarried 
in France. It is formed into millstones and then 
exported to all parts of the world. Most of the stones 
now used in our Rice mills for grinding rice are French 
Buhrstones. In the beds exposed at Aiken, alluded 
to above, we find the same fossil shells and corals as 
are contained in the Santee Marls exposed in the low 
country ; but what is most remarkable, and almost 
marvellous to the general reader, the rock is not 
like the Santee Marl, calcareous; that is to say, @ 
lime-rock, but the shells and corals or corallines, have 
been converted into a flint or silicified mass, each shell, 
coral or fossil preserving its original shape and size 
and retaining every wrinkle, indentation or other 
characteristic of the original. This change caused 
by a chemical agent, has converted a mass of lime 
rock, or Calcareous Marl into a Bufhrstone or silicious 
indurated Marl rock, and is analogous to the con- 
version of the rocks of the “ Upper” Ashley Marl, 
of the same age, (Eocene,) formed under the same 
conditions as were those of the Santee Marls, but 
subjected ultimately to the effects of two distinct and 
independent geological agents, thereby producing 
two distinct kinds of rocks, one a flint-like rock, 
(Buhrstone,) whose silex (or flint) was derived from 
the surrounding sand hills of that region, (Aiken,) 
the other (a Phosphate-rock) whose Phosphoric 
essence was derived from animal matter under the 
influence of which its chemical character was 
changed. 
