We use cookies to show content based on your preferences. If you continue to browse you accept their use and installation. More information. >

FMF - Friends of Minerals Forum, discussion and message board
The place to share your mineralogical experiences


Spanish message board






Newest topics and users posts
25 Sep-18:40:06 Re: please help! shiny dark green crystals (Steve Maslansky)
25 Sep-16:25:16 Re: please help! shiny dark green crystals (Alfredo)
25 Sep-15:47:28 Re: please help! shiny dark green crystals (Kevin Schofield)
25 Sep-15:23:57 Re: please help! shiny dark green crystals (Danieljp)
25 Sep-15:21:31 Re: please help! shiny dark green crystals (Danieljp)
25 Sep-14:56:23 Re: please help! shiny dark green crystals (Riccardo Modanesi)
25 Sep-11:42:50 Re: please help! shiny dark green crystals (Alfredo)
25 Sep-09:27:30 Re: please help! shiny dark green crystals (Danieljp)
25 Sep-09:18:00 Re: please help! shiny dark green crystals (Alfredo)
25 Sep-09:14:53 Re: please help! shiny dark green crystals (Bob Carnein)
25 Sep-09:05:41 Re: please help! shiny dark green crystals (Danieljp)
25 Sep-08:58:57 Re: please help! shiny dark green crystals (Danieljp)
25 Sep-08:38:32 Please help! shiny dark green crystals (Danieljp)
25 Sep-04:49:26 Re: collection from dany mabillard (Dany Mabillard)
24 Sep-23:53:53 Re: collection of volkmar stingl (Volkmar Stingl)
24 Sep-16:03:11 Re: a mineralogical trip through italy by sante celiberti (Sante Celiberti)
24 Sep-14:19:12 Re: collection of volkmar stingl (Philippe Durand)
24 Sep-13:33:45 Re: collection of michael shaw (Michael Shaw)
24 Sep-05:53:12 Re: collection from dany mabillard (James Catmur)
24 Sep-04:44:51 Re: collection from dany mabillard (Dany Mabillard)
23 Sep-23:18:54 Re: collection of volkmar stingl (Volkmar Stingl)
23 Sep-22:10:18 Re: collection of volkmar stingl (Volkmar Stingl)
23 Sep-16:40:43 Re: help me please, sounds like metal (Lou B.)
23 Sep-15:44:45 Re: help me please, sounds like metal (Matt_zukowski)
23 Sep-15:39:10 Re: a mineralogical trip through italy by sante celiberti (Sante Celiberti)

For lists of newest topics and postings click here


RSS RSS

View unanswered posts

Why and how to register

Index Index
 FAQFAQ RegisterRegister  Log inLog in
 {Forgotten your password?}Forgotten your password?  

Like
72388


The time now is Sep 26, 2020 00:35

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
When can a fossil be also considered a mineral?
  Goto page 1, 2, 3  Next
  Index -> The Ten Thousand Club
Like
10


View previous topic :: View next topic  
Author Message

Carles Millan
Site Admin



Joined: 05 May 2007
Posts: 1297
Location: Catalonia


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 03:53    Post subject: When can a fossil be also considered a mineral?  

In https://www.mineral-forum.com/message-board/viewtopic.php?p=31223#31223 Don Lum wrote:
Opal var Shell Opal
Belemnite

From that post an interesting question arises. When can a fossil be also considered a mineral?
Back to top
Reply to topic Reply with quote
Like
   

Don Lum




Joined: 03 Sep 2012
Posts: 2338
Location: Arkansas


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 09:58    Post subject: Re: When can a fossil be also considered a mineral?  

Carles Millan wrote:
Don Lum wrote:
Opal var Shell Opal
Belemnite

From that post an interesting question arises. When can a fossil be also considered a mineral?


Carles isn't opal SiO2? I think that the animal, in this case related to the cuttlefish and has an exoskeleton, has been replaced in part by opal which is a mineral. What do you think?

_________________
hogwild
Back to top
Reply to topic Reply with quote
Like
   

Carles Millan
Site Admin



Joined: 05 May 2007
Posts: 1297
Location: Catalonia


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 15:32    Post subject: Re: When can a fossil be also considered a mineral?  

Don Lum wrote:
Carles Millan wrote:
Don Lum wrote:
Opal var Shell Opal
Belemnite

From that post an interesting question arises. When can a fossil be also considered a mineral?

Carles isn't opal SiO2? I think that the animal, in this case related to the cuttlefish and has an exoskeleton, has been replaced in part by opal which is a mineral. What do you think?

Indeed I don't know what I think about this. Just would like to learn what wiser people in the forum are thinking about a fossil being also a mineral. Some ammonites are made of pyrite, you very probably know. Are they a fossil, a mineral, or both? If they were a true mineral, what about the rest of fossils, many of which (I guess) are made of calcium carbonate? Could one speak, for example, of pyrite pseudomorph after ammonite?
Back to top
Reply to topic Reply with quote
Like
   

Don Lum




Joined: 03 Sep 2012
Posts: 2338
Location: Arkansas


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 17:08    Post subject: Re: When can a fossil be also considered a mineral?  

I don't know if there are any wiser people on the Forum than you, Carles. In any event I don't have anymore specimens like that to post.

Sincerely,

Don

_________________
hogwild
Back to top
Reply to topic Reply with quote
Like
   

Mark Ost




Joined: 18 Mar 2013
Posts: 516
Location: Virginia Beach


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 17:55    Post subject: Re: When can a fossil be also considered a mineral?  

That is an interesting question as many fossils are permineralized with minerals replacing the original material that was biogenic. On the other hand the definition of a minerals is a non-organic substance with definite but not fixed orderly structure and chemistry. I suppose the definition hinges on if the specimen is of biological origin and was itself alive. That claim cannot be made of say feldspar or tourmaline. Of course some minerals are the result of biogenic action but they were never, by definition, alive.

I suspect this is a lot like the planet debate as there is no real concrete definition of planet outside of the Greek origin "Planitos"

This is a toughie.
Back to top
Reply to topic Reply with quote
Like
   

Cesar M. Salvan
Site Admin



Joined: 09 Jun 2008
Posts: 113
Location: Alcalá de Henares


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 17:59    Post subject: Re: When can a fossil be also considered a mineral?  

Carles, If I got the point that drives your question, there are some cases of minerals that are true fossils itself. An example is the Fichtelite (C19H34). From a chemical point of view, Fichtelite is a saturated cyclic hydrocarbon and is a fossil form of some bioterpenoids, mainly from conifer resins. The Fichtelite, apart of a mineral, is a "molecular fossil". Other examples are Simonellite and Hartite.

So to the question 'when can a fossil be also considered a mineral?' the response is when the existence of the mineral itself depends on the fossilization process. i.e. the mineral does not exist apart of a fossilization. As in the case of fichtelite.
We consider these minerals as molecular fossils because we can trace the chemical structure to the original, biological structure. But caution, not all organic minerals are molecular fossils.



fichtelita alemania.jpg
 Description:
Fichtelite
Wampen, Thiersheim, Marktredwitz, Fichtelgebirge, Franconia, Bavaria, Germany
FOV 2.5 mm
The fichtelite, a classic molecular fossil that is an accepted mineral species as well.
 Viewed:  26763 Time(s)

fichtelita alemania.jpg



untitled (2).jpg
 Description:
The transformation of the original, biological material (abietic acid) in the mineral Fichtelite and the non-mineral (yet) Retene.
 Viewed:  26732 Time(s)

untitled (2).jpg


Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 698
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 19:17    Post subject: Re: When can a fossil be also considered a mineral?  

The basic definition of a mineral is that it is a naturally occurring inorganic chemical. The question of biogenic origin leads to all kinds of philosophical knots.

Sulfur crystals may precipitate when bacteria act on naturally occurring hydrogen sulfide or hydrocarbons; are these minerals? What about pyrite, which may result from bacterial action?

Brachiopods produce shells made of fibers of calcite, with minor if any organic matter between them. During diagenesis, the organic matter is replaced by calcite. Is the replacing calcite a mineral, but not the biologically-precipitated fibers?

Echinoderms produce porous plates of single crystal calcite; during diagenesis the pores fill epitactically with calcite to form complete single crystal plates, easily detected in limestones because of the calcite cleavage. Are these (even the infilling) not minerals because the template was formed by biological action, and the template dictated the orientation of the later infilling?

Many clams and other mollusks make their shells at least partly of aragonite, which often is replaced in the fossil by calcite, which is often blocky and preserves none of the subtle texture of the original shell. Is this calcite a mineral?

What about minerals that form in voids inside clam shells - anapaite and vivianite come to mind?

The ultimate perspective is recent work (sorry, I should be able to quote a source, but I can't) which points out that early biological evolution produced photosynthesizing primitive plants that led eventually to an oxygen-rich environment, which is a major factor in forming most of the known minerals - many oxides and hydroxides, sulfates, carbonates, phosphates, etc.

The question of whether silicified ammonites or brachiopods or pyritized trilobites or ammonites are minerals hangs on whether the precursors are minerals or not. If the precursors are minerals, then the replacements are minerals. If the precursors are excluded because of a biological influence, then the argument about the replacements starts all over again. What a pain!!!

My own perspective is that if an inorganic chemical substance originates as a consequence of biological activity, and it is known to occur in nature (e.g. calcite and aragonite, pyrite) without immediate biological mediation, it is a mineral. Unless it is known to have been formed by intentional or artificial intervention by humans (e.g. growing zincite or antimony or silver or suifur crystals, or abandoning tin cans and lead batteries in environments where they lead to micro-cassiterite or cerussite formation in the midst of a vast region of innocent sedimentary deposits) we must consider these things to be minerals. Slag heaps are certainly an important special case. Inorganic chemicals known only as direct biological precipitates are up for discussion.

My opinion and one Euro can perhaps buy you a good cup of coffee....

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 698
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 19:23    Post subject: Re: When can a fossil be also considered a mineral?  

Mark Ost wrote:
(snip) I suppose the definition hinges on if the specimen is of biological origin and was itself alive. That claim cannot be made of say feldspar or tourmaline.


At Mont Saint-Hilaire, a noted igneous intrusion into paleozoic rocks near Montreal, I found an indisputable brachiopod, probably identifiable to genus if not species, replace by pectolite and amphibole, from a carbonate xenolith; and other brachs are found in the hornfels replaced by vesuvianite. Not feldspar or tourmaline, to be sure, but pretty close!

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

Mark Ost




Joined: 18 Mar 2013
Posts: 516
Location: Virginia Beach


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 20:54    Post subject: Re: When can a fossil be also considered a mineral?  

Ha! Oh yes; I have to be careful as there are so many exceptions and fuzzy areas. Tourmaline just popped into my head as most likely not having any connection to biogenesis. I once asked a professor how we could really say anything since it seemed we knew so little. His astute answer was they don't give degrees for saying nothing at all.
Back to top
Reply to topic Reply with quote
Like
   

Mark Ost




Joined: 18 Mar 2013
Posts: 516
Location: Virginia Beach


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 21:07    Post subject: Re: When can a fossil be also considered a mineral?  

Lead batteries lead to micro cassiterite?................oh man, I could show you the yellow brick cassiterite road then! 127,000 ppm of lead (soil) in a road underlain by old car batteries ground up. Maybe I should open a cassiterite mine!


256.JPG
 Description:
Maybe cassiterite, certainly lead
not at liberty to say
600 feet
 Viewed:  26591 Time(s)

256.JPG


Back to top
Reply to topic Reply with quote
Like
   

Pete Richards
Site Admin



Joined: 29 Dec 2008
Posts: 698
Location: Northeast Ohio


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 21:24    Post subject: Re: When can a fossil be also considered a mineral?  

Mark Ost wrote:
Lead batteries lead to micro cassiterite?................oh man, I could show you the yellow brick cassiterite road then! 127,000 ppm of lead (soil) in a road underlain by old car batteries ground up. Maybe I should open a cassiterite mine!


If I'm doing the math right, 127,000 ppm is 127 parts per thousand or 12.7% lead. I'd open a reclamation project!

If it has turned to cassiterite, it's probably fairly stable. Better yet, if it has altered to pyromorphite, there is no hazard at all to speak of. Throw a bunch of bone meal on it, and let it bind up.

But it's a shame that it's there in the first place!

_________________
Collecting and studying crystals with interesting habits, twinning, and epitaxy
Back to top
Reply to topic Reply with quote
Like
   

gemlover




Joined: 31 Dec 2008
Posts: 211
Location: Easley, SC


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 13, 2013 22:31    Post subject: Re: When can a fossil be also considered a mineral?  

Personal viewpoint: The fossil may be composed of mineral, but it is not itself a mineral, it is a cast, etc. of the animal. A fossil may also be composed of mud or other materials, that may not be a single mineral. I guess it is a discussion of semantics.

JOHN

_________________
John
John Atwell Rasmussen, Ph.D.. AJP
Geologist and Gemologist
Back to top
Reply to topic Reply with quote
Like
   

Carles Millan
Site Admin



Joined: 05 May 2007
Posts: 1297
Location: Catalonia


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 03:10    Post subject: Re: When can a fossil be also considered a mineral?  

Don Lum wrote:
I don't know if there are any wiser people on the Forum than you, Carles.

By the hundreds !
Back to top
Reply to topic Reply with quote
Like
   

Carles Millan
Site Admin



Joined: 05 May 2007
Posts: 1297
Location: Catalonia


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 03:23    Post subject: Re: When can a fossil be also considered a mineral?  

Mark Ost wrote:
Lead batteries lead to micro cassiterite?

I don't think so. If lead becomes cassiterite, then we could speak of nuclear transmutation from lead to tin, an even more interesting topic.
Back to top
Reply to topic Reply with quote
Like
   

Mark Ost




Joined: 18 Mar 2013
Posts: 516
Location: Virginia Beach


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 03:39    Post subject: Re: When can a fossil be also considered a mineral?  

I would prefer transforming it to gold. Actually mining is not too far from how it was removed!
Back to top
Reply to topic Reply with quote
Like
   

Cesar M. Salvan
Site Admin



Joined: 09 Jun 2008
Posts: 113
Location: Alcalá de Henares


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 03:58    Post subject: Re: When can a fossil be also considered a mineral?  

Quote:
The basic definition of a mineral is that it is a naturally occurring inorganic chemical.


And what about the organic chemicals that are defined as minerals, like the cited Fichtelite?

Quote:
Just would like to learn what wiser people in the forum are thinking about a fossil being also a mineral. Some ammonites are made of pyrite, you very probably know. Are they a fossil, a mineral, or both?


Fossil and minerals are not excluding categories. A fossil composed by one mineral, is a mineral. And a fossil. You can not claim "pyrite pseudomorph after ammonite" because "mineral" regards to its chemical nature and "fossil" regards to its origin. As 'gemlover' said, the fossil is a cast and, hence, the same biological origin could lead to different mineral assemblage after fossilization.

I insist, the only cases I know of minerals that are also fossils themselves (i.e. in which "mineral" and "fossil" are not separate categories or definitions) are organic minerals like Fichtelite.
Back to top
Reply to topic Reply with quote
Like
   

Philip G




Joined: 13 Aug 2009
Posts: 54
Location: North Lancashire, England


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 05:12    Post subject: Re: When can a fossil be also considered a mineral?  

Hi all,

I have always found this specimen quite interesting.

The pictures show what i believe to be hematite encasing a solitary rugose coral but leaving the fossil itself totally unhematised. The small cavity in the coral contains micro crystals of dolomite.

From the Carboniferous limestones, Florence Mine, Egremont, West Cumbria, England.

Philip



foss-hema-flor3.jpg
 Description:
Hematite
Florence Mine, Egremont, Cumbria, England
12 cm x 9 cm
 Viewed:  26396 Time(s)

foss-hema-flor3.jpg


Back to top
Reply to topic Reply with quote
Like
   

alfredo
Site Admin



Joined: 30 Jan 2008
Posts: 797


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 07:01    Post subject: Re: When can a fossil be also considered a mineral?  

Fossils could be divided into two types:

1) The dead organism's original organic material is preserved without replacement, as for example with Siberian mammoths frozen for 20,000 years, or giant ground sloths merely desiccated in dry caves, or human beings pickled in the acid waters of peat bogs. These fossils are NOT minerals, obviously.

2) The much more common type of fossil in which the original organic matter is replaced by mineral matter. These are obviously both fossils and minerals, and any distinction is merely semantic and due to the collection preferences of the person who has it. I'm sure most MINERAL collectors would not consider a fossil to be a mineral SPECIMEN unless it contained either visible crystals or some interesting replacement species (opal, vivianite, etc). A fossil composed of clay minerals is of course also a mineral, but few mineral collectors would consider it to be a mineral "specimen".

The definitions of "mineral" and "fossil" are pretty well established and it would be redundant to rehash them here, so what this discussion is really about is the definition of "specimen"!
Back to top
Reply to topic Reply with quote
Like
   

Cesar M. Salvan
Site Admin



Joined: 09 Jun 2008
Posts: 113
Location: Alcalá de Henares


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 07:14    Post subject: Re: When can a fossil be also considered a mineral?  

Alfredo, you forgotten the common case of fossils in which organic material hasn't been replaced by inorganic materials, but without preservation of original organic components. Is the case, for example, of amber (not mineral) or, again, fichtelite (a mineral).
Back to top
Reply to topic Reply with quote
Like
   

Elise




Joined: 22 Dec 2009
Posts: 243
Location: New York State


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: May 14, 2013 07:38    Post subject: Re: When can a fossil be also considered a mineral?  

Hi Pete!

Maybe that was Bob Hazen's work? See our thread here: https://www.mineral-forum.com/message-board/viewtopic.php?p=13282#13282

Cheers
Elise

Pete Richards wrote:

The ultimate perspective is recent work (sorry, I should be able to quote a source, but I can't) which points out that early biological evolution produced photosynthesizing primitive plants that led eventually to an oxygen-rich environment, which is a major factor in forming most of the known minerals - many oxides and hydroxides, sulfates, carbonates, phosphates, etc..


_________________
Elise Skalwold
Back to top
Reply to topic Reply with quote
Like
   
Display posts from previous:   
   Index -> The Ten Thousand Club   All times are GMT - 5 Hours
Page 1 of 3
  Goto page 1, 2, 3  Next  

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


All pictures, text, design © Forum FMF 2006-2020


Powered by FMF