New Jersey Cretaceous

[wetwilly]

Hi,

 

Looking over my bin of unknowns from the Brooks, I wanted to verify if what I have is a concretion or not.  It is not what I typically find so I thought I would post it for some opinions.

 

It's about 1-1/2" wide and approximately 1/8" thick.

 

Thanks. 

[Fossildude19]

Looks slag-like to me. 

 

Wait for some other opinions, though. 

Regards,

[ynot]

I think it is a nice piece of Hematite.

It should have a red streak.

Tony

[belemniten]

18 minutes ago, ynot said:

I think it is a nice piece of Hematite.

It should have a red streak.

Tony

Hematite was also my first thought ....

[wetwilly]

Tried the streak test for possible hematite - no reddish brown streak ( test left a black or grayish streak). 

 

Leaning toward slag. 

 

Thanks for replies. 

[ynot]

Slag is a glass like residue of metal refining and does not leave a streak. A gray/black streak would indicate another iron oxide, possibly goethite. 

Tony

[squali]

I have found similar specimens and I now believe them to be similar to limonite concretions.  I don't know the specific mineral composition.  All are a combination of iron.  They are found near less permeable contacts like a clay sand interface.  I still have one I swear is a croc scute.

[ynot]

1 hour ago, squali said:

 

I have found similar specimens and I now believe them to be similar to limonite concretions.  I don't know the specific mineral composition.

 

Limonite is also an iron oxide (geologist term for rust.). It has a rust color streak and has the reddish/brown color of rust. Limonite can be in alternate layers with other iron oxides.

Tony

[wetwilly]

On 12/8/2016 at 8:12 PM, ynot said:

Slag is a glass like residue of metal refining and does not leave a streak. A gray/black streak would indicate another iron oxide, possibly goethite. 

Tony

Thanks Tony - good info. 

 

On 12/8/2016 at 9:34 PM, squali said:

I have found similar specimens and I now believe them to be similar to limonite concretions.  I don't know the specific mineral composition.  All are a combination of iron.  They are found near less permeable contacts like a clay sand interface.  I still have one I swear is a croc scute.

I was thinking it was some kind of scute myself,  but something didn't seem right to me. 

 

Thanks Squali.