Basic tests

[val horn]

There are some basic explanations and tests that will help people get started in fossil hunting  and there are some real experts who should be writing this instead of me  but i will start and others can correct or add to this as needed.  A burn test is a check of how recent the fossil is.  A modern bone placed in a flame will burn and smell bad while  fossil bone will not burn or scorch or smell like burning hair,

 

limestone sea shells will bubbles dissolve in dilute hcl but bone will not.  This will definitely separate  many bone imposters from bone.

 

a comment on sandstone  sand stone as implied by the name is made up of tiny grains visible by eye or with a 10 x jewlers loop.  Fossils can make an impression in sand sandstone and fossil imprints can form sandstone casts  but a fossil bone is not going to be made up of sandstone

 

 

[Rockwood]

1 hour ago, val horn said:

Fossils can make an impression in sand sandstone and fossil imprints can form sandstone casts  but a fossil bone is not going to be made up of sandstone

A natural cast of bone could in theory be sandstone. It's going to be really rare though. 

[val horn]

A cast is a fossil, but it isnt a bone.

 

 

 

 

 

[Rockwood]

14 minutes ago, val horn said:

A cast is a fossil, but it isnt a bone.

 

 

 

 

 

Sure it is. It's just at the extreme end of the replacement spectrum. Unaltered bone found in a cave would represent the other end. 

[patelinho7]

3 hours ago, Rockwood said:

Sure it is. It's just at the extreme end of the replacement spectrum. Unaltered bone found in a cave would represent the other end. 

 Couldn’t a cast be theoretically created by the infill of a space created by the bone that long since broke down? That would be a true cast, not any kind of mineral replacement of the bone. 

[Rockwood]

5 hours ago, patelinho7 said:

 Couldn’t a cast be theoretically created by the infill of a space created by the bone that long since broke down? That would be a true cast, not any kind of mineral replacement of the bone. 

The bone was in a place. Now sand is in that place. Sand is a mineral. Why is that not mineral replacement? 

[val horn]

1. No Sandstone  is a type of rock .sand is a sediment.  Silica is a mineral.  Silica can be dissolved.  Silica can be part of many rocks , like opal and quartz, and  many different sediments such as clay and sand.  .   Silica can fill in pore space.  Silica can  fill in cracks .  Silica can give you petrified wood, agatized bone, and opalized fossils . this is not sandstone.  

[patelinho7]

If you categorize sandstone casts as mineral replacement, you are close to saying a positive track impression is a mineralized foot, in my opinion. And I know, a track is created while the animal is alive while a “bone cast” is after death. But the preservation process is the same, along with many other trace fossils. I see mineral replacement as a chemical process that specific to the chemical makeup of the bone itself as well as the depositional environment. Sandstone casts do not care about chemical makeup of the bone. 

[Rockwood]

I can't really disagree with the terminology, but I think it's important to realize that the whole exercise is really just a way to navigate what is actually a continuum.  

[ynot]

Sure am glad I am not a newbie collector, because Y'all got me way confused here.

Edited June 15 by ynot

[val horn]

Sorry

[ynot]

15 hours ago, val horn said:

 A burn test is a check of how recent the fossil is.

A burn test will only determine if a bone is recent, it will not age a fossil. Also, if it smells it is not a fossil.

[Rockwood]

2 hours ago, ynot said:

Sure am glad I am not a newbie collector, because Y'all got me way confused here.

It's really quite simple. It can be sandstone and still also be a fossil which represents a bone. It's not going to be common though. 

[Rockwood]

2 hours ago, ynot said:

A burn test will only determine if a bone is recent, it will not age a fossil. Also, if it smells it is not a fossil.

A modern bone that has been cooked will sometimes give a false test result. 

[DPS Ammonite]

3 hours ago, ynot said:

Also, if it smells it is not a fossil.

Animal bones frozen in ice probably will smell when burned even when they are considered fossils (over 10k years old). 
 

One paper suggests that ice caps could be up to 5 million years old.

https://www.sciencenorway.no/antarctica-climate-ice/the-oldest-known-ice-in-the-world-can-be-found-here/2318504#:~:text=Ice in Antarctica has been,to five million years old.

 

Could there be 5 million year old bones that smell when burned?

Edited June 15 by DPS Ammonite

[patelinho7]

Meanwhile, some modern bones give false positives and do not smell