
NEW YORK SHELL CLUB NOTES NOS2267 December 1980 Page 3 
“TURRITELLA" 
To most rockhounds, Turritella means 
a ripple of discussion about the correct generic term's being Gonio- 
basis, but Turritella stuck. Now, "Th 
eters pe Nhat eee ° e Keystone " 
Horace D. Thomas, State Geoldalacdor Pe i Newsletter" quotes 
"Turritella agate." There was 
"The fossil snail in 'Turritella agate' does not belong to the 
genus Turritella, which is a marine snail. The cdate Moonee 
from Eocene rocks in the Green River Basin, Southwestern 
Wyoming, which are of fresh-water origin. 
"We always have referred this snail to the i i 
genus Goniobasis 
but recent word from Dr. W. H. Bradley of the U. S. Geological 
Survey indicates that it properly belongs to the genus 
Oxytrema. 
"Just how the name 'Turritella Agate' came to be applied to 
the rock 1s a mystery. I have imagined that some rockhound 
identified the snail as Turritella because it is high-spired 
and superficially like that genus. The name, then, may have 
been perpetuated. 
"The oval structures are probably one of two things, both of 
which are known to occur in this rock. If they are circular 
in cross-section and have a concentric structure they are 
oolites. If they are ovate and lack concentric structure, 
they may be fossil ostracods. If any of the surfaces of your 
specimens are not polished, ostracods there might look like 
minute pelecypods (bivalves or clams) - they are bivalved and 
have hinge line. Maybe both occur!" 
Goniobasis or Oxytrema, rockhounds call it Turritella! 
Reprinted from THE LAMIT V(5):10, May 1975 
TYPES OF FOSSIL PRESERVATION 
Fossils are preserved in different ways, and some knowledge of these 
processes will help you understand your specimens. The entire ani- 
mal or plant may be preserved without alteration: this is called 
ENTIRE PRESERVATION. When minerals, precipitated from ground water, 
fill the openings in shell or bone, long after the flesh of the 
animal has decayed, the shell or bone becomes heavier and harder; _ 
this process is called PERMINERALIZATION. The ground water may dis- 
solve away some or all of the mineral matter in bone or shell and» 
replace it with other minerals that water carries in solution; this 
is called REPLACEMENT. It may be encased in rock and all the liq- 
uids and oi1S in its body may be squeezed out; this process 15 
called DISTILLATION. When plants are preserved by squeezing, they 
are called COMPRESSIONS. The ground water seeping through the rock 
may dissolve the shell or bone completely without replacing it with 
other minerals. In that case, if the rock has hardened before the 
fossil is dissolved out, the rock retains the imprint of the fossil 
making a MOLD. Sometimes the mold is later filled with mineral mat- 
ter, producing a CAST, which is a replica of the original fossil in 
different material. 
From GALCO PEBBLE PATTER via others and re- 
printed in THE LAMIT V(5):9, May 1975 of 
The Norfolk Gem and Mineral Association 
