Looking for ID, possible moss agate??

[Mnagate34]

I found this the other day while looking in a pile of rock. The reddish inclusions with White banding look like this might be a Moss Agate but I am unsure. There is a section that is clearly quartz with a light purple tint to it but I am wondering what the rest of the body is. Any help would be appreciated. Found in Central Minnesota.

 

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[Eu_citzen]

Can't really tell from the pic. Break it open with a hammer - if it looks waxy you might just have a chalcedony.

 

[old digger]

Your rock specimen does not have the characteristics that are attributive to moss agate. It does show the low qualities of a lesser valued agate due to the large quartz fracturing.

 

[Mnagate34]

So if it doesn't have the characteristics of moss agate, but it shows small banding and the fracturing of quartz does that mean that some rocks can have a small amount of agate in it? Granted the whole nodule might not be an agate but there could be a small amount of agate in it? Or is it a different material that creates the layers of depth? Is that just silica? Or something else? You'll have to excuse my inexperience as I am new to rockhounding..... all your answers are greatly appreciated, thank you.

 

[IAMZIM]

The banding usually indicates a fortification agate, moss agate has dendritic inclusions that can look "fern" like or "tree" like as well as other forms. To me, it looks like the whole nodule is agate, or chalcedony, it's just that it's probably a fortification agate, not a moss agate.

<---Fortification agate

<----Moss agate

 

[gunsil]

Get someone to slice it up for you, it may have some nice patterns inside. Google up lapidary clubs in MN, they usually have people who will slice up rocks for a small fee. If it has really nice patterns or dendrites (moss) they could also then polish any good slices for you, and if there are several good slices you could likely trade a slice for the work performed.

 

[Mnagate34]

I understand most properties of what is in Moss Agate but unfortunately I am one of those people that have a hard time just chopping into a rock to see the inside. I think that most of the time you can see a hint of what might be inside by small fractures or what the husk looks like. I have found other agates that fit the typical moss agate (1st photo) criteria but some are just different such as the the second photo where it has the branch like attributes but they seem much less plentiful. The reddish inclusions on my original post reminded me of this agate but I was unaware since I have a whole nodule rather than just a small piece.

 

[Eu_citzen]

So if it doesn't have the characteristics of moss agate, but it shows small banding and the fracturing of quartz does that mean that some rocks can have a small amount of agate in it? Granted the whole nodule might not be an agate but there could be a small amount of agate in it? Or is it a different material that creates the layers of depth? Is that just silica? Or something else? You'll have to excuse my inexperience as I am new to rockhounding..... all your answers are greatly appreciated, thank you.

To state it simply:
Quartz-Chalcedony-Agate/jasper are all related and all silica. They are the same thing with difference mostly in crystal structure.
You can find large Quartz crystals, but you'll never find large chalcedony crystals. (in fact, most chalcedony is microscopic crystals)
Agate/jasper are varieties of chalcedony which is a variety of quartz. Sort of a family.

They certainly are interchangeable, in fact in amethyst geodes you often find a outer band of chalcedony which then goes over to amethyst crystals.

 

[Mnagate34]

To state it simply:
Quartz-Chalcedony-Agate/jasper are all related and all silica. They are the same thing with difference mostly in crystal structure.
You can find large Quartz crystals, but you'll never find large chalcedony crystals. (in fact, most chalcedony is microscopic crystals)
Agate/jasper are varieties of chalcedony which is a variety of quartz. Sort of a family.

They certainly are interchangeable, in fact in amethyst geodes you often find a outer band of chalcedony which then goes over to amethyst crystals.

So any difference should be obvious to the naked eye? I shouldn't need a microscope to be able to determine the difference, or is there something more apparent that would show up through a microscope that would help decipher the differences between them? Sounds like branding a difference in Agate/Jasper & Chalcedony is in the eye of the beholder speaking strictly about crystal structure, they are all too closely related to really seperate them unless the obvious banding or inclusions are apparent. It seems like so many people attach "trade-names" to these sorts of rocks to classify them that one would think they could be filed neatly into certain categories but with so many different variances they simply cannot all be called the same thing or fall under the same category. Correct me if I am misunderstanding but Silica can basically just act like a filler material, but as far as classification goes the rest is just up to the process of the creation of the rock (creations of bands or inclusions) and from there it can be further classified from whats obvious?

 

[Eu_citzen]

So any difference should be obvious to the naked eye? I shouldn't need a microscope to be able to determine the difference, or is there something more apparent that would show up through a microscope that would help decipher the differences between them? Sounds like branding a difference in Agate/Jasper & Chalcedony is in the eye of the beholder speaking strictly about crystal structure, they are all too closely related to really seperate them unless the obvious banding or inclusions are apparent. It seems like so many people attach "trade-names" to these sorts of rocks to classify them that one would think they could be filed neatly into certain categories but with so many different variances they simply cannot all be called the same thing or fall under the same category. Correct me if I am misunderstanding but Silica can basically just act like a filler material, but as far as classification goes the rest is just up to the process of the creation of the rock (creations of bands or inclusions) and from there it can be further classified from whats obvious?

I suggest you familiarize yourself slightly with mineral identification; Moesia has an excellent post on the subject. Use the search function.
Most of the time, yes. Chalcedony quite rarely shows a glassy luster, as quartz will. In fact, most chalcedony I've seen has a waxy luster to it.

To, again simplify it: Agate is a chalcedony with concentric banding, jasper is an opaque chalcedony.
If you are uncertain, you may accurately call it chalcedony. But you need to see the luster of the rock in question, as it is one of the properties we look for during identification. To see luster you need a freshly exposed surface, i.e. get a hammer to it!

The trade names are more a thing to aid in selling it, IMO.

Classification by how they were formed is important for rocks, not minerals.
For minerals we use the properties Moesia explained in his post, although certainly it can aid in identification.
Garnets for example are quite common in metamorphic rocks.

 

[Mnagate34]

I suggest you familiarize yourself slightly with mineral identification; Moesia has an excellent post on the subject. Use the search function.
Most of the time, yes. Chalcedony quite rarely shows a glassy luster, as quartz will. In fact, most chalcedony I've seen has a waxy luster to it.

To, again simplify it: Agate is a chalcedony with concentric banding, jasper is an opaque chalcedony.
If you are uncertain, you may accurately call it chalcedony. But you need to see the luster of the rock in question, as it is one of the properties we look for during identification. To see luster you need a freshly exposed surface, i.e. get a hammer to it!

The trade names are more a thing to aid in selling it, IMO.

Classification by how they were formed is important for rocks, not minerals.
For minerals we use the properties Moesia explained in his post, although certainly it can aid in identification.
Garnets for example are quite common in metamorphic rocks.

Yes as a newbie there is a lot for me to learn, thank you very much for your patience and willingness to point me in the right direction!

 

[Aurora]

Thanks Everyone.
I too have been struggling with chalcedony, agate and jasper. |
Great information for us newbies.

 

[gunsil]

I think a better definition is that agate is translucent chalcedony and Jasper is opaque chalcedony. Agate does not have to have concentric banding, it may have "plumes" or "moss" (dendrites), and can and often has concentric banding (fortification), but can also just be translucent without dendrites or fortification patterns. Both agates and jaspers can come in all or many colors. Gem silica (often called gem chrysocolla) is a beautiful translucent blue chalcedony colored by copper minerals, and chrysoprase is a green translucent chalcedony colored by manganese, and neither of these gem quality translucent chalcedonies have dendrites or fortification patterns.

 

[Eu_citzen]

If you ever delve deeper into the subject, I think you'll find even many whom are not quite in agreement over the agate/jasper/chalcedony thing.
And the ever increasing use of trade names make it ever further confusing. As hobbyists I suppose we have to simplify.

Did you for example know that "Fire agate" is in fact chalcedony, rather then agate?

As a side note, chrysoprase is colored by Nickel.

 

[DDancer]

Quite the debate indeed. Hahh! I'll add that coloration, patterning and structure are typically whats used to make definitions between different silicates. Silicates form in different ways depending on heat of the solution they come from, the presence of other minerals that typically add coloration as well as changes by heat due to metamorphism. Quite the grab bag however knowing your localities geologic offerings and understanding their formation can lend a strong hand to identifying many silicates in all their forms.