( Singular nouns: Fr- fossile-riche
stein; Rus- ... )
FOSSILIFEROUS ROCKS (See also the
A. Iridescent nacreous aragonite outer
layers of a fossil
ammonite (Placenticeras meeki), from Bearpaw Formation exposures
on the Kormos
Farm, Magrath, Alberta, Canada. This material, which exhibits
qualities and color intensities (cf. "B"), occurs
the vicinity of Lethbridge, Alberta, Canada. Pieces incorporated
in jewelry have
been marketed as ammolite, calcentine and korite. Canadian Museum of
Nature. (© photo
by Frederick H. Pough)
B. Iridescent aragonite. Pendant (greater
dimension - 4.0 cm)
of ammolite with fractured outer layer of a fossil ammonite (Placenticeras
from near Lethbridge, Alberta, Canada. (© courtesy of Korite
C. Fossil favosites coral carved and
polished to resemble a
porcupine (height - ca. 10 cm).(photo by D.L. Brittain)
D. Petoskey stone pendant (greater
dimension - ca. 5.0
cm). (© photo by Dick Dietrich)
E. Petrified wood, Petrified Forest
National Park, Arizona. (©
photo by Dick Dietrich)
F. Fossiliferous rock. Well prepared and
in part polished
slab (height - ca. 100 cm) with diverse Mesozoic cephalopods.
Comstock Rock Shop,
Virginia City, Nevada. (© photo by Sue Monroe)
G. "Turritella" agate polished piece --
see at end
of OTHER NAMES list.
DESCRIPTION: The term fossiliferous rock
may be applied to
any fossil-bearing rock. Those mentioned herein are only a few examples
of many that have
been used as gemrocks. Some fossiliferous rocks have been
selected for use as
gemrocks because of the identities of their contained fossils; others
have been chosen
because of the patterns their included fossils give when cut in certain
name usually applied to these rocks in the marketplace is the name of
the rock preceded by
either the name of the predominant fossil (e.g., coraline
marble) or the
adjective fossiliferous if the rock contains more than one kind of
fossil with none
predominant (e.g., fossiliferous limestone). Several other
have been used, most of them based either on the locality from which
the rock came or
someone's idea of a term that might increase sales of anything made
from the rock. Because
each of these gemrocks is so-to-speak unique, descriptions, noteworthy
are included in the comments given after several of the materials
listed under the OTHER
- Agatized coral - silicified coral from the
Ballast Point area of Tampa Bay, Florida that has been fashioned into
jewelry and ornaments.
- Agatized wood - silicified wood, most of which
is chalcedony or jasper from several localities. Most of the
petrified wood that is so- designated doesn't have the characteristics
of agate; for accuracy, each piece should be called by its
correct name -- e.g., chalcedonized wood, jasperized wood
or, perhaps even better/safer, just silicified wood.
- Ammolite (calcentine, korite) -
trade names given to vibrantly iridescent bits of the nacreous
aragonite layers fossil ammonites (Placenticeras meeki/Placenticeras
intercalare) that occur in the Late Cretaceous Bearpaw Formation
near Lethbridge, Alberta, Canada. Marketed as "One of Nature's
rarest gems" and dubbed "Grandmother of Pearl" (Pough, 1986), this
material has been fashioned into gemstones used in rings, brooches etc.
For an extensive, well illustrated description of this material,
see Mychaluk, Levinson and Hall (2001); for an update, see Mychaluk, 2009.
Many of the fashioned
cabochons (etc.) are assembled stones -- see under SIMULANTS
- Baculites - members of this genus of extinct ammonites, especially
those that have been pyritized -- e.g., internal molds that consist largely of the mineral pyrite
(= "fool's gold") -- have been use as pendants etc. At least one of these was marketed "as (spelled
phonetically) 'declenite', and [indicated to have grown] ... in
smoke/steam stacks of chemical processing plant or factory in eastern
Europe." (Jenesa Spiva, email dated Jun 11, 2008). By the way,
some people refer to baculites -- especially those that are relatively
long -- as "walking stick rocks."
- Beckite - a general term sometimes applied to
several different silicified fossil-bearing rocks that have been used
- Bethersden marble - a dove-gray to reddish
brown limestone that contains fossil snail shells, possibly of
freshwater origin, from England.
- Bone turquoise - fossil bones or teeth colored
blue by some iron phosphate -- see under SIMULATES subheading in
- Calcentine - see Ammolite.
- Chinarump - name sometimes given to petrified
wood from Arizona.
- Coraline marble (or limestone) - a number of
diverse coral-bearing rocks have been fashioned as cabochons for
jewelry and carved (and often also polished) into diverse ornaments. A
few of them have been given special names -- two examples are Petoskey
stone and Ogwell marble.
- Crinoid "stems" - segments of fossil crinoid
"stems", which are thick-walled circular cylinders (commonly with star-shaped
central holes). Sometimes referred to as "Indian beads" because
of their use by pre-Columbian native Americans, today these stem
segments continue to be used as beads, especially by beachcombers but
also by some jewelry designers, who incorporate them in "arty"
necklaces and bracelets.
- Cycad - an exceptionally fine silicified
example, found along the eastern side of the Henry Mountains, about 25
miles south of Hanksville, Wayne County, Utah exhibits an amazing
array of diverse colors along with diamond-shaped configurations
- Dinosaur bone agate - an overall red,
brown or rarely dark blue, chiefly silica material that exhibits a
pattern that resembles a fine-grained breccia with the larger lighter
colored fragments surrounded by a relatively sparse darker matrix,
which, respectively, are thought to represent porous bone and hard bone
matrix. (A few pieces represented as this material have other
colors, probably as the result of dyeing.) Many specimens
fashioned into, for example, cabochons have come from Arizona,
Colorado, New Mexico, Utah, and Wyoming.
- [Dinolite - this name has been
introduced for composites that consist of ammolite, dinosaur bone,
sugilite and turquoise and/or malachite that have been crafted into ,
for example, pendants (Mychaluk, 2009).]
- Dinosaur bones replaced by carnelian have been
found in Dinosaur National Monument in northwestern Colorado and
adjacent Utah, east of Vernal, Uintah County, Utah.
- Dinosaur dung - bookends marketed as such were
noted as "fossilized droppings . . . millions of years old and
probably the most remarkable accent piece you can find. Your friends
will be amazed (and amused)." One has to wonder about the taste
of both the merchandiser and anyone who buys such pieces, eh (?).
- Encrinite (also encrinal or encrinital
marble) - term(s) applied widely to crinoid-rich, for the most part
stems, calcareous rocks that take a good polish -- examples are the
so-called bird'seye marble quarried at Iowa City, Iowa; the
crinoid-bearing limestone of the Lambert Ranch in San Saba County,
Texas; and a widely known one from Derbyshire, England.
- Figure stones - a widely applied name,
especially in the past, to all sorts of fossiliferous rocks, many of
which are mimetolithic.
- Fire marble - a brown limestone from Bleiberg,
Carinthia, Austria that is characterized by sporadic areas that exhibit
firelike appearances as the result of reflections emitted from included
fossil shells that are chatoyant.
- Fossil pearls - dark olive green and
brownish "pearls" that appear to represent Melo and/or conch pearls
(one of which appears to have been a blister pearl) are recorded and
illustrated in Anonymous (nd.); my attention was directed to them
by Bruno Jordan (personal communication, 2006).
- Fossil rock - a term that could be used for
virtually all of the gemrocks treated in this entry.
I actually saw this simple designation applied to a fossil-rich
rock, the identity of which I did not check, from Baja California,
- Fossilipherous - trade name, used as a noun,
for diverse fossil-bearing rocks fashioned into ornaments. In my
opinion, this term tops the list so far as inanity!.
- Goniobasis agate - "About 20 per cent of the
results of a Google search on the work 'turritella' [q.v.] are Goniobasis agate." (Allmon,
- Griotte - name given to a fine-grained,
reddish colored, goniatite-bearing limestone.
- Korite - see Ammolite.
- Lens stone - fossiliferous limestone from
vicinity of Caen, France; actually used more as a facing stone
than as a gemrock, a fine example of this rock may be seen where it
graces the walls of the vestibule and reception foyer of the National
Academy of Sciences building, Washington, D.C.
- Lithoxyle, lithoxyl and lithoxyli - terms
sometimes applied to opalized wood in which the original woody
structure is well-preserved.
- Lumachelle - iridescent fossil pelecypod
shells that occur within a dark gray or brownish marble that occurs in
the vicinity of Bleiberg, Kärnten, Austria.
- iridescent ammonite from Madagascar that has been fashoined into
cabochons and various other shapes have been marketed under this name
- Ogwell marble (also Red ogwell marble)
- a limestone containing fossil favosites (corals) from Devonshire,
- Oolitic (or pisolitic) cherts and limestones -
these rocks from several localities have been tumbled, cut and polished
as cabochons for jewelry, or carved into such things as fetishes.
- Opalized wood - term applied widely to
silicified wood that consists largely to wholly of opal.
Typically, this material constitutes only part of any given silicified
- Petoskey stone (sometimes called Petoskey
agate) - colonial rugose coral (Hexagonaria percrinata)
within rocks and as beach pebbles derived from those rocks in the
region around and generally south of Petoskey, Emmet County,
Michigan. Typically gray or grayish tan, these rocks' use as
gemrocks depends upon their patterns: Cabochons for jewelry are usually
cut to exhibit the characteristic hexagonal pattern formed
perpendicular to the direction of growth of these corals; some carvings
and ornaments, however, are fashioned also to exhibit the pattern
of relatively long subparallel lines parallel to the direction of
growth -- e.g., mushrooms with hexagonal-patterned caps
and linear stems. A recent
report (Robinson and Reed, 2013) records Petoskey stones with
diversecolors -- i.e., "... from almost white to tan, dark
gray, or brown, with darker colorations presumably due to higher
petroleum content. The rarest coloration, however, is a pink hue
that may be restricted to a small area of the stone or saturate the
entire stone. [However,] Only one in perhaps three hundred to
five hundred stones will show a pink color. ... Most [of which] show a
mottled pigmentation, ... " They conclude that the pink
coloration is due to the presence of iron, probably hematite.
- Petrified live oak - this silicified wood,
some with wood-borer holes, has also been found here and there within
this same region as is listed for Petrified palm wood, the next listed
- Petrified palm wood - orange-tan, reddish
brown, medium brown, and multicolored silicified palm wood.
Materials so identified have been given a number of names such as opal
wood, palm root agate and jasperized palm. Most have come
from unconsolidated rubble of Tertiary and Quaternary terraces and
gravel deposits in eastern Texas, Louisiana, Mississippi and Alabama,
inland from the Gulf of Mexico and also in southern Arkansas.
- Petrified wood in general - most petrified
wood consists largely of one or more of the silica minerals/rocks
(including opal). This has led to frequent, and more prudent, use
of the general term silicified wood. Some petrified wood
faithfully preserves such features as bark structures, wood grain, and
even pith of the precursor wood. Many especially well preserved
specimens of petrified wood have been found within volcanic ash
deposits from which the silica appears to have been derived. Petrified
wood with precursors of several diverse species and also petrified
cones and related ferns and cycads have found use as gemrocks. Other
names used include names such as agatized wood (= wood agate),
jasperized wood (=xyloid), and opalized wood (xylopal,
lithoxyle, lighoxyl or lighoxylite). A well known locality
for petrified wood, most of which is best characterized as jasper, is
the Petrified Forest National Park, east of Holbrook, Arizona;
another well-known occurrence is the petrified forests near
Cairo, Egypt. Items have been fashioned from diverse petrified
wood rough of several different colors, with a greenish blue seemingly
the most eagerly sought (see Quinn, 2004).
- Shell agate - agate containing silicified
mollusc shells. An especially well known example is "Turritella"
agate, a highly siliceous rock so-to-speak chuck full of gastropods
(Elimia tenera) <>replaced by chalcedony. Most of this
material is chalcedony or jasper rather than either of the varieties of
chalcedony usually characterized as agate. This fact not
withstanding, much so-called shell agate used for fashioning costume
jewelry and diverse ornaments has been recovered in Wyoming.
- Silicified wood - a good, all-inclusive,
noncommital term used for silica-rich petrified wood -- it can be
used to describe, for example, the so-called agatized woods, wood
replaced by either chalcedony or jasper, opalized wood, and all
combinations of such petrified wood.
- Stingray coral - white, gray and blue-gray
fossilized Favosites coral from a Silurian reef "exposed in the
intertidal zone of a remote island off the coast of Alaska's Prince of
Wales Island" that has been fashioned into polished slabs and used for
"inlay[s] in men's accessories such as rings, tie tacks and cufflinks."
This marketplace name is said to have been chosen because the pattern
exhibited on surfaces cut perpendicular to the "cells" resembles that
of stingrays' skins. (Laurs, 2002, p.93).
- Turritella agate - See Shell agate. -- This is
one of the most widely used fossiliferous gemrocks. Attention is
directed to the article by Allmon (2009) in which he states "
'Turritella agate' is not what its name says it is: it is not
agate, and it is not made of fossil snails of the marine genus Turritella."
G."Turritella" agate polished piece
(width - 4 cm), Wamsutter Ridge, southwestern Wyoming. (© photo by
courtesy of Webminerals s.a.s., www.webgemshop.com)
USES: Necklaces (dating to ca. 28,000 B.C.) that include
fossilized pelecypods and gastropods as beads have been recorded
from a Gravettian Culture site at Pavlov, which is about 25 km west of
Jihlava in central Czech Republic (Dubin,1987). More recently, several
gemrocks that are best designated as
fossiliferous rocks have
been used as the "rough"
for fashioning gemstones -- usually for larger pieces such as brooches,
buckles and ornament bars for bolo ties; many of these rocks have
also been used as
the rough material
from which both functional (e.g., buttons, dishes, bowls and
picks) and diverse
decorative ornaments (e.g., carved figurines for "whatnots")
fashioned. Another group of objects that falls into this category
of uses comprises
the decorative rocks created by the ultra-fine preparation of
that contain either individual or groups of fossils; several such
specimens are displayed
in offices and homes because of their so-to-speak artistic appearance
and/or value as
conversational pieces rather than because of their scientific (i.e.,
paleontological) value -- see Figure F and examples shown in
(1999). Also, dinosaur bones have been fashioned into such things
as pendants, ear rings and cuff links. In addition,
individual fossils -- e.g.,
trilobites and brachiopods carefully removed from their host rocks --
have been used as
pendants by merely drilling holes in or through them for insertion of a
post, loop or
chain, and some of these kinds of individual fossils have been used to
make molds for, for example,
gold castings that are used as pendants, earrings,
also directed to the statement about the clams that are replaced
at least in part by carnelian -- see Chalcedony entry, under the
H. Ammonite pendant.
This cephalopod (41 cm. -
height as shown) is from Madagascar.
sliced to show the internal
structure of its shell before being mounted for use as a pendant.
The reverse (out) side exhibits a multicolored sheen similar to that
exhibited by mother-of-pearl. The necklace to which it is attached is
faceted tigers-eye. (© photo by
courtesy Gail Coppock, http://www.gailsart.com/Jewelry.html)
OCCURRENCES: Most fossils occur in
sedimentary rocks; a few
occur in volcanic rocks; fewer occur in the metamorphosed
products of these
rocks; [and] some petrified plants and animals have been found in
LOCALITIES: Widespread -- a few examples
are noted in the
statements following the terms listed under the OTHER NAMES subheading.
REMARKS: I have
always been somewhat nonplussed about the
origin -- or
perhaps more, the general application -- of the term fossil: It
comes from the Latin fossilis(dug
up), and my observations and experience indicate that fossils are
less frequently dug up than minerals and rocks, and especially
ores. To add to my bewilderment, I early learned that Georgius Agricola
(Georg Bauer, 1494-1555) is widely recognized as the "Father of
Mineralogy" because of his classic De
Natura Fossilium, which is widely
considered to be the first textbook of mineralogy. In any case,
since at least the middle 1600s, the term fossil has been applied
almost exclusively to remains of plants and animals, most of which have
been so-to-speak lithified.
The Petoskey stone and the city in Emmet County, in
the northwestern part of Michigan's lower peninsula, were named after
Chief Ignatius Petoskey (1787-1885) who founded the community.
Petoskey's father was a French fur trader and his mother was an Odawa
(Ottawa) Indian. His first name
Ignatius was bestowed upon him by Jesuit missionaries; his Odaw name was, as spelled by the Indians -- in order make it
closer to their ponounciation -- was Biidassige or Pe-to-se-ga, which translated
means "One who brings light" or "Light shines through." In any
case, his name became recorded as Ignatius Petoskey. One has to
wonder if "Biidassige stone" or even "Petosega stone" would
have gained the wide recognition that Petoskey stone has.
Ammolite (etc.), much of
which occurs in
relatively thin pieces, is commonly impregnated with a polymer to give
them strength and,
in some cases, increase the depth of their diverse colors -- see Figure
The name buffalo stone was given by North
Indians to fossils considered to be charms that would insure those who
success while hunting buffalos.
Petrified wood is Arizona's representative among
the nearly 200 commemorative "stones," including at least one from each
of the 50 states, that are
mounted inside the Washington Monument.
The Petoskey stone is the official state stone of
Petrified wood is the state fossil of Arizona, the state stone of
Mississippi, and the
state gem of Washington.
Teredo petrified wood is the state fossil of North Dakota. Petrified palmwood is the state
stone of Texas. The "sea scorpion,"
the euripterid Eurypterus remipes,
is the state fossil of New York.
SIMULANTS: As indicated by a story
frequently repeated within
the geological community -- although apparently not wholly correct
(Sanders, 1960) --
fakery of fossils is nothing new: Briefly, that story holds
that several of
the "fossils" described and figured by Johann Bartholomaeus Adam
Professor of Natural History, University of Wurzburg -- in his treatise
"Lithographiae Wirceburgensis" (1726) were carved by students, who
where he would find them, which he did, only later to learn he had been
the spokesman for a hoax. Another such hoax that involves the
Giant," first reported as a fossil man, is described in the third
paragraph under the
REMARKS subheading in the ALABASTER entry.
Assembled ammolite - strictly speaking, these
units are not
silimulants. They are triplets -- e.g., a "Triplet,
a glass top and mosaic inlay of natural fossilized ammonite shell
fragments with a thick
black backing," (Johnson et al., 2000, p.261-262).
assembled stones can be seen to be such by examination with a
handlens; also, the
glass of this one has a superior hardness (H. ~5).].
***Glass - a glass bead apparently made to
limestone is illustrated by Liu (1995, p.222). - [appearance].
***Plastic (in part) -The following are hybrids
simulants per se. -- Whereas most cabochon ammolite doublets
and triplets have a
thin slice of ammolite along with one or two plastic layer(s), in some
of the more
recently marketed ones, the ammolite layer consists of a plastic-bound
mosaic of small
fragments of ammolite (Johnson et al., 2000).
***Resin - Two examples: 1.Winterthur has
recently advertized and
illustrated 12-inch spheres ("faux seashell sculpture[s]") the surfaces
are covered with mollusc-shaped masses in relief. 2.Design
Toscano has recently
advertized some cast resin faux fossil display pieces as follows:
remains of two fossilized creatures thought to be Dragons, arrived at
our offices via a
mysterious Parcel Post. . . We opened the . . . wooden crates, and
unfolded the burlap . .
. to discover bas-relief, two-toned . . . dragon fossils unearthed in
Wales and sent by
Dr. Rex Solomon, an eccentric British anthropologist. . . . [you can be
the owner of and
thrilled by] the 'authenticity' of these [fossils]." -
[Appearance suffices for
any of these I have seen; if one is undecided, check with a
Snake skin agate - misnomer applied to some
chalcedony within lava
(?) that roughly resembles snake skin -- e.g., those from
Grants area, Cibola
County, New Mexico. - [Appearance suffices.].
***Two additional examples of so-to-speak
falsifying fossils are
noted in the AMBER entry, under the SIMULANTS subheading.
Also, see "fossil turtles" under the REMARKS
the SEPTARIUM entry.
REFERENCES: No general reference.
BUT a number of
paleontology and historical geology textbooks contain indirectly
about fossils and their occurrences; examples are Black, 1988 -
Wicander and Monroe, 1993 - stratigraphy.
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update: 8 July 2013
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