Back to Ganoksin | FAQ | Contact

Agatized dinosaur bones


#1

Hi guys,

Someone has posted oodles of pictures of agatized dino bones.

http://www.flickr.com/photos/gembone/sets/72157600549999346
http://www.flickr.com/photos/gembone/sets/72157594292965876

Elaine
http://www.CreativeTextureTools.com


#2

Pretty pictures. An agate is an agate. How does dino bone become an
agate?

KPK


#3

Kevin,

The same way that wood turns to stone (agate) and becomes petrified
wood… over time, the process of organic decay in exactly the right
conditions allows the organic material to be replaced by minerals in
the same configuration as the original piece of wood. Ultimately, the
petrified wood “becomes” quartz and has the same characteristics and
Mohs hardness. In the case of the dino bone, I believe what happens
is that the “soft” organics are replaced by the minerals and the hard
organics that don’t decay remain in place. So what you have is a
porous grid of dino bone filled with stone.

A really neat process and the resulting product is quite beautiful
and interesting.

Karen Goeller
No Limitations Designs
Hand-made, one-of-a-kind jewelry


#4
Pretty pictures. An agate is an agate. How does dino bone become
an agate? 

Good question, I wondered that too. I suppose they are the bone
version of petrified wood and they look like agate so the person
called them that.

Elaine
http://www.CreativeTextureTools.com


#5
Pretty pictures. An agate is an agate. How does dino bone become
an agate? 

Presumably because, like many mineral deposits, some agates are
formed after being deposited by silicates dissolved in water. It
fills voids in the dinosaur bone and is left behind in layers - hence
the banded agate examples in the pictures. You can also clearly see
examples of amethyst crystals in some of the pictures.

Helen
UK


#6

In the case of dinosaur bones I believe it would be
permineralization. The mineral that agate is grouped in would have
been disolved in water and circulated through the sediment untill it
wound up filling in the open cell structure of the dinosaur bones.
This in turn would have increased the likely hood of the whole bone
to fossilize as it streangthened the total structure and protected
it from colapse and furthur decay. The part of the bone that was
solid would then have undergone replacement by minerals as well. If
the permineralized part is later replaced it blures details and
makes identification more difficult but sometimes, particularly with
very large specimens like dinosaurs, it is still possible.

Now please understand that even though I have paleo training it is
in invertibrate fossils of the early cambrian, and I gave up
paleontology for metalsmithing and am therefor a little rusty,
particularly on those vertebrate dinos. I may have the orders of
what part fossilize first wrong. However, as far as I understand
bones, the rest is hopefully correct. And I know I should remeber
what mineral grouping agate is in but this late at night I grow
fuzzy.

Other popular fossilized organisims, that are often agatized, and
frequently used in jewelry include but are not limmited to,
ammonites, coral, bivalves, molusks, brachiopods, and wood.

Angela


#7

Dino bone is colored by trace minerals. My point is that a dino bone
is not an agate.


#8

Karen

My point is that stone does not equal agate;

But I agree that "what you have is a porous grid of dino bone
filled with stone. 

I use that beautiful red/orange dino bone in some of my designs.

Kevin


#9

Elaine, no offense

But as has been pointed out previously, accuracy matters. One can’t
decide to arbitrarily use one term to describe something other.

An agate is a particular stone. There are avid agate collectors world
wide who would be upset that dino bone would be called an agate.

KPK


#10

For those interested in Agatized dinosaur bone,there was an
interesting program on the Science Channel a week or so ago regarding
preserved soft tissue.“Conventional wisdom among paleontologists
states that when dinosaurs died and became fossilized,soft tissues
didn’t preserve”,(from Science Daily). I also found this on the
internet on the Science Daily web site.It seems that a
Paleontologist,an assistant professor of Paleontology at North
Carolina State University, Dr. Mary Schweitzer, has succeeded in
isolating soft tissue from the femur of a 68 million year old
dinosaur.For those interested this can be found at

http://www.sciencedaily.com/releases/2005/03/050325100541.htm

It seems that dino bone is gaining in popularity for
jewelry,especially the red cell and pastels.Found it at Neiman
Marcus even.

John Barton


#11

Kevin,

I’m NO expert so this is just me theorizing. No it’s not an agate in
itself but its cavities are “invaded” by silicates in solution and
the silicate ions get deposited so that agate gets built up in the
cavities. Presumably when the organic compounds decay, the structure,
made from calcium compounds remains - but that in itself is very
spongy and therefore receptive to mineral deposits such as the
silicates.

There’s a lot of supposition in my email, hoping that someone with
more knowledge of the fossilization process will respond please. This
is a fascinating thread Elaine.

Helen
UK


#12
But as has been pointed out previously, accuracy matters. One can't
decide to arbitrarily use one term to describe something other. 

Absolutely.

I didn’t decide to call it that, I was merely sharing the website
with the nice pictures. As someone with GIA training, I am certainly
interested in the correct identification and naming of things.

Dinosaur bones are outside of my area of study, so I just quoted the
owner of the material.

I didn’t have the time to research the correct name for this stuff,
and the matter has been handled here quite nicely by the group. Now
we all know what it is and what it isn’t. Problem solved.

Elaine
http://www.CreativeTextureTools.com


#13

Kevin,

Are you saying that the cavities are filled with stone, but that the
stone isn’t agate? Many of the photos I saw close ups of, certainly
looked like some type of agate. It had the distinctive banding and
colouration of agate. And you could see the amethyst crystals in
some pictures, also part of the agate or silicon dioxide family of
minerals.

Are there other stones that resemble the banding of agate in the
colours shown?

Helen
UK


#14
An agate is a particular stone. There are avid agate collectors
world wide who would be upset that dino bone would be called an
agate. 

So, once dino bone has been fossilized (as all we have has been),
what stone is it? Isn’t is agate, at least some of it? I have a
piece that is pyritized-- the “cells” are iron pyrite-- beautiful!
Don’t know what the rest of it is, but quartz seems likely, doesn’t
it? Isn’t petrified wood quartz too? The colors in the stuff I
collected in Arizona sure look like agate-- same colors as mookaite.

Noel


#15
My point is that a dino bone is not an agate. 

[Trying to mediate here] I believe that everyone is right here,
though I’m a little rusty on my geology - be gentle. Agate is a form
of cryptocrystalline quartz, and “agatized dinosaur bone” is that.
Kevin is saying, I believe, that “Agate” is a specific variety of
cryptocrystalline quartz, kind of like “all ducks are birds but not
all birds are ducks.” It could be argued all day long that all
cryptocrystalline quartz is agate, but Kevin is correct at least from
some point of view - “True” agate is a certain “species” of rock. Me,
I say what’s in a name, but then we need names, too…

http://www.donivanandmaggiora.com


#16

Perhaps a better term would be dinosaur bone replaced by chalcedony.

Rose Alene


#17

fossil bone has a very distinctive microstructure, consisting of
tubular, branching haversian canals, each of which has a laminated,
concentric structure, and in well-preserved material, cavities and
tiny caniculi left by individual bone cells are visible at high
magnification. Some of this distinctive structure is visible by
examination with the naked eye or a hand lens, but it becomes
blatently obvious with modest magnifications of only 10-100x.

Perhaps the most diagnostic feature, visible even at low
magnification and with poor preservation, is the clear tubular
geometry of the haversian canals. They are also clearly segregated
with respect to size, with the largest, millimetre-sized tubes in the
centre of the bone, and diminishing in size towards the margins. Even
without the other features, this should be easily recognizable,
although there would be potential for confusion with some types of
vascular plant structure if the preservation were too poor. The
laminated structure and cavities left from the bone cells would be
one distinguishing feature, and most vascular plants also have
comparatively thin cell walls with distinctive pores (tracheids). In
addition, many plant remains will have some carbonized plant material
representing the cell walls, while bone is completely mineralized,
whether it is unaltered or not.


#18
For those interested in Agatized dinosaur bone,there was an
interesting program on the Science Channel a week or so ago
regarding preserved _soft tissue. 

G’day; I was a bit reluctant to join this, but I quote the above
from an orchidist mailing, but the underline is mine. I ask ‘since
when is bone - any bone, been regarded as soft tissue?’

Bone is the hardest part of of any animal. When alive animal bone has
cells filled with soft tissue, which soon rots away, leaving the bone
porous and so able to absorb a fossilising mineral which will
preserve it for millions of years. And agate is a silica based hard
material left in and around the bone when the liquids have left.
Thus, whilst the soft material in the bone is gone for ever, the
silica based material has taken it’s place and the place of any
actual bone, which may also have gone.

Cheers for now,
JohnB of NZ


#19
Are there other stones that resemble the banding of agate in the
colours shown? 

In general the process of fossilization is replacement of organic
material with minerals. While in many cases the replacement mineral
is quartz and therefore is the name agatized, it does not have to
be.

Another class of fossilized material called marbleized. That is where
replacement materials are carbonates like calcite, dolomite, and
siderite.

Another group which can participate in the process are actinolites.
These include barite, pyrite, and etc.

These are not exclusive, but simply a few examples. It all depends on
mineral composition of the rock where process takes place.

In sedimentary deposits with high clay contents - replacement with
pyrite will be encountered frequently.

In volcanic rocks - replacement with chalcedony will be found often.

So, all the different opinions on the subject are technically
correct.

Leonid Surpin.


#20
An agate is a particular stone. There are avid agate collectors
known as (droolers among dealers) world wide who would be upset
that dino bone would be called an agate. 

Do you all remember the principle of “outlining” from grade school?
The most general comes first, then subdivisions, and the
subdivisions of those subdivisions.

Since my numerous references to John Sinkankas and his book “Gem
Cutting” continue to be ignored I will paraphrase.

The most general heading for the material under discussion is
’quartz’, then there is ‘crystalline’ varieties and
cryptocrystalline varieties and so on for a number of pages. One of
the last entries 'Petrified Wood, Coral, etc. reads “When buried in
the ground, some vegetable and animal remains are replaced by mineral
substances, commonly calcite or chalcedony.”

So the material that precipitated this discussion is a sub-variety of
quartz and it is dino bone, but it doesn’t fall under the quartz
division of agate.

Thus ended the lesson. But perhaps not this thread.

I think we getting calcified; so keep those moving parts moving.

KPK