Can a Fossil be Quartz ?

[Clintols]

I’m batting a 1000 with my identifications. This I know will continue my streak I’m sure. However I need to know if fossils can become crystal. Can a bone and tissue become quartz?

[Fossildude19]

Nope.

This is definitely a rock, and not a fossil.

[Mark Kmiecik]

Fossils cannot be quartz because of the conditions necessary for quartz to form. Check the Wikipedia listing for quartz for more info.

[Rockwood]

A fossil composed of quartz would have to be a natural cast, or a geodized fossil. 

[Ludwigia]

Fossils can become silicified, i.e. turned into quartz or "achatized" due to a process called permineralization. The sample you are showing us is in my opinion however not a fossil.

[anonaddict]

i agree that this particular rock is not a fossil, and that this isn't how a fossil preserved as quartz would look but it is not correct to say fossils cannot be preserved as quartz or even that it's uncommon. agatized fossils are very common. I cant speak for bones since most my fossils are shells due to living underwater but flint is a type of quartz and thats one of the most common types of rocks to find sea urchins in. even if strictly dealing with crystallized quartz ive seen a fair few of those

[Fossildude19]

2 hours ago, anonaddict said:

i agree that this particular rock is not a fossil, and that this isn't how a fossil preserved as quartz would look but it is not correct to say fossils cannot be preserved as quartz or even that it's uncommon. agatized fossils are very common. I cant speak for bones since most my fossils are shells due to living underwater but flint is a type of quartz and thats one of the most common types of rocks to find sea urchins in. even if strictly dealing with crystallized quartz ive seen a fair few of those

 

This is a bit of a misstatement.

 

Chert/Flint are Cryptocrystaline rocks, and Quartz is a crystaline mineral, but they are not quite the same.

So, it is incorrect to say quartz can make up fossils.

 

Chert and flint start out as Sedimentary rocks, but Quartz does not. That is why you can find fossils in chert or flint. Fossils form in Sedimentary rocks.

Can they become agatized, chertified, or be covered in beekite (a form of Chalcedony) yes, but not quartz.

 

In science it is best to be as specific as possible. I may be spitting hairs, but there are so many types of quartz and crystal structures, that it is best to be as clear as possible.

 

So, no fossils in quartz. 

[FranzBernhard]

6 minutes ago, Fossildude19 said:

but not quartz

Now I am going to split a hair .

 

What about those famous silicified fossils some members here are regularly etching out of limestone?

 

Franz Bernhard

 

 

[Rockwood]

18 hours ago, Rockwood said:

A fossil composed of quartz would have to be a natural cast, or a geodized fossil. 

 

45 minutes ago, FranzBernhard said:

Now I am going to split a hair .

 

What about those famous silicified fossils some members here are regularly etching out of limestone?

 

Franz Bernhard

 

 

If actual crystals formed, would it not qualify as a natural cast? I'm not sure where the distinction between it and replacement would be drawn though. 

[Fossildude19]

1 hour ago, FranzBernhard said:

Now I am going to split a hair .

 

What about those famous silicified fossils some members here are regularly etching out of limestone?

 

Franz Bernhard

 

 

 

 

I'm not a geologist, so I can't really answer other than to say, not all silicates are quartz, but quartz is a silicate.  

[Ludwigia]

6 hours ago, Fossildude19 said:

Chert/Flint are Cryptocrystaline rocks,

 

I'm sorry, but I beg to differ. If you read the link you gave us, at the end of the first paragraph you'll notice that the cryptocrystalline crystals in chalcedony are defined as quartz crystals.

[FranzBernhard]

3 minutes ago, Ludwigia said:

If you read the link you gave us, at the end of the first paragraph you'll notice that the cryptocrystalline crystals in chalcedony are defined as quartz crystals.

Yeah, you can use petrographic or mineralogical nomenclature on these things.

 

What is calcite marble? A rock composed sometimes almost entirely of calcite. In a collection, the same piece could rest in a petrographic collection as "calcite marble" or in a mineralogical collection as "massive calcite". At least in my opinion .

 

Fran Bernhard

[Fossildude19]

21 minutes ago, Ludwigia said:

 

I'm sorry, but I beg to differ. If you read the link you gave us, at the end of the first paragraph you'll notice that the cryptocrystalline crystals in chalcedony are defined as quartz crystals.

 

 

Hm. Did not see that in my haste.   

However, it IS from Wikipedia.(not always the most accurate information.)   So I can't really vouch for the veracity of THAT part of the statement.

 

I can only say silica SiO2 is different from quartz SiO4.

 

And I will stand by my assessment of this rock being quartz and not a fossil.

 

 

[anonaddict]

14 minutes ago, Fossildude19 said:

 

 

Hm. Did not see that in my haste.   

However, it IS from Wikipedia.(not always the most accurate information.)   So I can't really vouch for the veracity of THAT part of the statement.

 

I can only say silica SiO2 is different from quartz SiO4.

 

And I will stand by my assessment of this rock being quartz and not a fossil.

 

 

i think we are all in agreement on this specimen being quartz and not a fossil, the conversation just moved to a more general perspective on whether fossils can be preserved as quartz.

 

agree on wikipedia, i find myself often using it due to its high placement in search results but it is not reliable, text books written by experts are way more reliable

[FranzBernhard]

57 minutes ago, Fossildude19 said:

I can only say silica SiO2 is different from quartz SiO4.

Silica is a chemistry term for the compound SiO2.

 

Quartz is also SiO2. But you are right, quartz is structurally composed of SiO4-tetrahedrea forming a framework, with oxygens shared by two silicons.

Franz Bernhard

Edited Monday at 07:27 PM by FranzBernhard

[anonaddict]

18 minutes ago, FranzBernhard said:

Silica is a chemistry term for the compound SiO2.

 

Quartz is also SiO2. But you are right, quartz is structurally composed of SiO4-tetrahedrea forming a framework, with oxygens shared by two silicons.

Franz Bernhard

ohh that makes sense, and that is why crystals have repeating structures?

[Ludwigia]

Link

[Coco]

I agree that quartz is SiO2.

 

Coco

 

[FranzBernhard]

9 hours ago, anonaddict said:

and that is why crystals have repeating structures?

Other way around :

- When the SiO4-tetrahedra form an ordered, periodic, repeating network / structure, you have a crystal with an XRD-pattern with sharp reflections.

- When the SiO4-tetrahedra form an irregular, chaotic(??) network /structure, you have SiO2-glass with no sharp reflections in XRD.

- There are also things in between, semiordered states, of course.

Franz Bernhard

Edited Tuesday at 04:54 AM by FranzBernhard

[Brandy Cole]

I can't add much to the mineral makeup conversation but did have a piece that I pulled out for another thread with an example of what I had previously considered permineralization by quartz.  Now I'm not sure. 

 

The white structure does shimmer, but I had a hard time getting the lighting right to pick that up.