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
27 Mar-19:47:08 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Pete Richards)
27 Mar-16:15:44 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-15:18:59 Re: 2 unknowns co-occurring with caledonite, grand reef mine, az (Alfredo)
27 Mar-14:39:29 2 unknowns co-occurring with caledonite, grand reef mine, az (Cfrench58)
27 Mar-05:21:48 Re: the mim museum in beirut, lebanon (Mim Museum)
27 Mar-05:03:26 Re: trying to find information on rose/pink quartz and tourmaline associations. (Ning)
27 Mar-02:39:50 Re: the mim museum in beirut, lebanon (Tobi)
27 Mar-00:23:28 Re: collection of volkmar stingl (Volkmar Stingl)
26 Mar-00:53:41 Re: collection of volkmar stingl (Volkmar Stingl)
25 Mar-13:32:10 Re: collection of michael shaw (Michael Shaw)
25 Mar-00:25:58 The mizunaka collection - quartz (Am Mizunaka)
23 Mar-13:35:22 Re: collection of firmo espinar (Firmo Espinar)
22 Mar-08:32:28 Re: collection of michael shaw (Michael Shaw)
22 Mar-04:20:41 Re: the mim museum in beirut, lebanon (Mim Museum)
21 Mar-22:49:19 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:47:40 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-22:45:25 Re: green seam. Looks like it in a state of decay. (Ning)
21 Mar-15:34:23 Re: the mizunaka collection - quartz (Am Mizunaka)
21 Mar-14:35:08 Re: jim’s mineral collection (Jim Wilkinson)
21 Mar-14:15:36 The 4th phoenix heritage mineral show (phms) hosted by mineralogical society of arizona (m (Chris Whitney-smith)
21 Mar-04:36:10 Re: the mizunaka collection (Tobi)
21 Mar-04:11:47 Re: jim’s mineral collection (James Catmur)
20 Mar-23:34:15 The mizunaka collection - quartz (Am Mizunaka)
20 Mar-18:13:16 Re: jim’s mineral collection (Jim Wilkinson)
20 Mar-14:06:43 Re: dry gill mine, caldbeck fells, cumbria, uk (Forrestblyth)

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
111799


The time now is Mar 28, 2024 01:39

Search for a textSearch for a text   

A general guide for using the Forum with some rules and tips
The information provided within this Forum about localities is only given to allow reference to them. Any visit to any of the localities requires you to obtain full permission and relevant information prior to your visit. FMF is strictly against any illicit activities related to collecting minerals.
Hollow geode; some with flint?
  
  Index -> The Ten Thousand Club
Like


View previous topic :: View next topic  
Author Message

dgc




Joined: 11 Jun 2008
Posts: 5

View user's profile

Send private message

PostPosted: Jun 11, 2008 15:24    Post subject: Hollow geode; some with flint?  

I've got several round & oblong rocks found in a field when I was young. They are similar to sandstone, kinda soft. Some are totally hollow; some have what sems like flint rock inside. What are these things?
Thanks!
Daren
Back to top
Reply to topic Reply with quote
Like
   

Joan R.




Joined: 16 Mar 2007
Posts: 75
Location: Barcelona


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 12, 2008 04:15    Post subject: Re: Hollow geode; some with flint?  

Hi Daren,

Without images is not easy to determinate what mineral or rock are you talking about. It would be much easier with some pictures. Please send some photo/s and perhaps we could try to identify them.

If you are talking about sandstones sometimes there are vugs originated by dissolution of organic materials, with Hematite crusts inside...but we need to see them.

BSRG
Joan

_________________
Joan Rosell
lengenbach(.)com
Grup Mineralògic Català
Back to top
Reply to topic Reply with quote
Like
   

dgc




Joined: 11 Jun 2008
Posts: 5

View user's profile

Send private message

PostPosted: Jun 12, 2008 18:10    Post subject: Re: Hollow geode; some with flint? PICS !!  

Here's some pictures. The ones I cracked open as a boy are long lost. Some were hollow with a dark lining and some were solid,, smooth gray, flint-like.


1 003.jpg
 Description:
 Viewed:  35491 Time(s)

1 003.jpg



1 005.jpg
 Description:
 Viewed:  35519 Time(s)

1 005.jpg



1 001.jpg
 Description:
 Viewed:  35507 Time(s)

1 001.jpg


Back to top
Reply to topic Reply with quote
Like
   

Joan R.




Joined: 16 Mar 2007
Posts: 75
Location: Barcelona


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Jun 13, 2008 02:44    Post subject: Re: Hollow geode; some with flint?  

Hi,
They are similar than river boulders. Sometimes the rounded rocks are embedded or included in limestone or sandstone. Of course, these boulders could have different lithogenic origins. Some could be only limestones (hydrochloric acid effervescence) or Quartz (lidites, silex...) and this materials could show vugs inside.

This is my personal opinion.

BSRG

_________________
Joan Rosell
lengenbach(.)com
Grup Mineralògic Català
Back to top
Reply to topic Reply with quote
Like
   

dgc




Joined: 11 Jun 2008
Posts: 5

View user's profile

Send private message

PostPosted: Jul 31, 2008 20:57    Post subject: Re: Hollow geode; some with flint?  

Anyone else have any info? Thanks!
Back to top
Reply to topic Reply with quote
Like
   

Les Presmyk




Joined: 06 Dec 2007
Posts: 372
Location: Gilbert, AZ

View user's profile

Send private message

PostPosted: Aug 01, 2008 09:45    Post subject: Re: Hollow geode; some with flint?  

Having cracked a few geodes over the years and any spherical rock that folks bring into the show, my first guess would be these are just river rocks. Or, as I tell people, all geodes are round rocks but not all round rocks are geodes. Not very deep, philosophically, but true. Geodes are not this smooth and I believe any that may be hollow or contain something inside are more of an accident than anything.
Back to top
Reply to topic Reply with quote
Like
   

Pete Modreski
Site Admin



Joined: 30 Jul 2007
Posts: 709
Location: Denver, Colorado


Access to the FMF Gallery title=

View user's profile

Send private message

PostPosted: Aug 01, 2008 13:05    Post subject: Re: Hollow geode; some with flint?  

Daren,
I agree that these look like they are probably, for the most part, just round "river rocks".

Some of them, perhaps the very spherical ones, could possibly be sandstone concretions; mineral-cemented nodules that form in sandstone. Such concretions can be solid sandstone, or sandstone around some harder central core, or around a fossil, or even hollow inside. Here, I'm posting a photo of a group of such concretions, from near Colorado Springs. Many of these are hollow, which in this case is due to them having once contained centers of pyrite, which has been oxidized and dissolved away, helping to provide the iron that cemented the concretion together. These are hollow, but they are not quite properly "geodes", because they are not lined with crystals inside, just a hollow shell of sandstone. Because such things are composed of fairly soft and friable (crumbly) sandstone, most of them are only found where they have weathered out "in place" from the host sandstone, and, unlike round river rocks which are made of hard quartzite, chert, granite, etc., they do not survive being transported very far by rivers or streams.

Sincerely, Pete



sandstone concretions.jpg
 Description:
iron oxide-cemented sandstone concretion, from near Colorado Springs, Colorado USA
 Viewed:  35298 Time(s)

sandstone concretions.jpg


Back to top
Reply to topic Reply with quote
Like
   

dgc




Joined: 11 Jun 2008
Posts: 5

View user's profile

Send private message

PostPosted: Aug 01, 2008 18:00    Post subject: Re: Hollow geode; some with flint?  

Thanks!
Back to top
Reply to topic Reply with quote
Like
   

dgc




Joined: 11 Jun 2008
Posts: 5

View user's profile

Send private message

PostPosted: Aug 01, 2008 18:01    Post subject: Re: Hollow geode; some with flint?  

Ive got a new friend with a slab saw - I may slice open a couple of them.
Back to top
Reply to topic Reply with quote
Like
   

wardp




Joined: 03 Sep 2008
Posts: 1
Location: Marshall, VA

View user's profile

Send private message

PostPosted: Sep 03, 2008 16:02    Post subject: Re: Hollow geode; some with flint?  

They look like what we used to call Glacier Eggs. You didn't find them in an area that was once covered by glaciers did you?

Just a thought.
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 1
    

 
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 2006-2024


Powered by FMF