lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 24, 2021 1:55:55 GMT -5
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Post by vegasjames on Dec 24, 2021 3:16:23 GMT -5
The white bubbly area looks like aragonite. And the brown translucent portion I would say is sard, which is a brown chalcedony.
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lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 24, 2021 14:44:06 GMT -5
The white bubbly area looks like aragonite. And the brown translucent portion I would say is sard, which is a brown chalcedony. Thanks for your response. I am not familiar with it but looked it up and seems like a good ID. So would all the white specks and lines throughout be aragonite? I am not good at identifying rocks yet so I appreciate the help.
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Post by RickB on Dec 24, 2021 17:01:51 GMT -5
Chert?
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Post by vegasjames on Dec 24, 2021 17:19:12 GMT -5
The white bubbly area looks like aragonite. And the brown translucent portion I would say is sard, which is a brown chalcedony. Thanks for your response. I am not familiar with it but looked it up and seems like a good ID. So would all the white specks and lines throughout be aragonite? I am not good at identifying rocks yet so I appreciate the help. No, the softer white bubbly stuff looks like aragonite. The glassier white vein would also be chalcedony.
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lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 24, 2021 19:20:44 GMT -5
I had originally thought chert as well but was looking for other suggestions as I am not great at IDs.
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Post by vegasjames on Dec 25, 2021 1:42:10 GMT -5
I had originally thought chert as well but was looking for other suggestions as I am not great at IDs. Chalcedonies are forms of quartz. Common chalcedony, agates, jaspers and chert/flint are all forms of chalcedony. All chalcedonies are the dehydration products of opal, but the sources of silica is one difference between common chalcedony as well as agates and jaspers, as opposed to chert/flint. The opals that form common chalcedony agates and jaspers derive their silica from inorganic sources such as sandstone or clays. When the source is clay they also pick up some aluminum oxide (AO). The higher the AO content the stronger and more stable the opal. Chert/flint on the other hand form from opals deriving their silica from biogenic sources such as diatomaceous earth. and is a sedimentary stone.
Opal itself starts out as a silica gel. As the silica molecules move closer and closer together, water starts getting squeezed out. When the remaining water content is 3-21% opal is the result. As the opal water content starts dropping below 3% it gains density and starts to crystallize forming in to one of the chalcedonies.
Common chalcedony comes in a wide variety of colors and patterns and can be very translucent to opaque.
Agates by definition are translucent chalcedonies with thin bands of varying colors. Many stones are still referred to as agates even though they do not fit the geological definition of agate, such as "moss agates" and "plume agates". Using names of specific stones loosely to identify any related stones is actually a common practice, but leads to a lot of confusion. For instance, when people call any unidentified copper ore "chrysocolla" or the use of the name "silicated chrysocolla" as this is not chrysocolla at all. It is a chalcedony stained by copper salts. Another is the common use of the name selenite, which is clear and non-fibrous form of gypsum, to identify satin spar that is a much more common fibrous and translucent to opaque version of gypsum.
Jaspers are an opaque version of chalcedony containing various impurities such as moganite.
Chert/flint is actually considered a type of jasper and is generally opaque although it can sometimes have a very slight translucence. Although again the word chert gets used loosely to identify some forms of chalcedony that are not really chert.
The reason I said this was sard is because is has too much translucency to be considered chert/flint. Sard is a brown colored chalcedony with more translucency than chert. I find quite a bit of sard in Southern California and Northern Nevada. The dark chocolate brown sard makes for some absolutely gorgeous cabs.
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Post by jasoninsd on Dec 25, 2021 1:50:14 GMT -5
I had originally thought chert as well but was looking for other suggestions as I am not great at IDs. Chalcedonies are forms of quartz. Common chalcedony, agates, jaspers and chert/flint are all forms of chalcedony. All chalcedonies are the dehydration products of opal, but the sources of silica is one difference between common chalcedony as well as agates and jaspers, as opposed to chert/flint. The opals that form common chalcedony agates and jaspers derive their silica from inorganic sources such as sandstone or clays. When the source is clay they also pick up some aluminum oxide (AO). The higher the AO content the stronger and more stable the opal. Chert/flint on the other hand form from opals deriving their silica from biogenic sources such as diatomaceous earth. and is a sedimentary stone.
Opal itself starts out as a silica gel. As the silica molecules move closer and closer together, water starts getting squeezed out. When the remaining water content is 3-21% opal is the result. As the opal water content starts dropping below 3% it gains density and starts to crystallize forming in to one of the chalcedonies.
Common chalcedony comes in a wide variety of colors and patterns and can be very translucent to opaque.
Agates by definition are translucent chalcedonies with thin bands of varying colors. Many stones are still referred to as agates even though they do not fit the geological definition of agate, such as "moss agates" and "plume agates". Using names of specific stones loosely to identify any related stones is actually a common practice, but leads to a lot of confusion. For instance, when people call any unidentified copper ore "chrysocolla" or the use of the name "silicated chrysocolla" as this is not chrysocolla at all. It is a chalcedony stained by copper salts. Another is the common use of the name selenite, which is clear and non-fibrous form of gypsum, to identify satin spar that is a much more common fibrous and translucent to opaque version of gypsum.
Jaspers are an opaque version of chalcedony containing various impurities such as moganite.
Chert/flint is actually considered a type of jasper and is generally opaque although it can sometimes have a very slight translucence. Although again the word chert gets used loosely to identify some forms of chalcedony that are not really chert.
The reason I said this was sard is because is has too much translucency to be considered chert/flint. Sard is a brown colored chalcedony with more translucency than chert. I find quite a bit of sard in Southern California and Northern Nevada. The dark chocolate brown sard makes for some absolutely gorgeous cabs.
Thank you SO much for taking the time to post information like this. I find it fascinating and it really does help people like me (geologically "challenged" LOL) have a better understanding of the "science"...of which I don't have the background. If I could like your post more than once, I would!
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lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 25, 2021 2:13:02 GMT -5
I had originally thought chert as well but was looking for other suggestions as I am not great at IDs. Chalcedonies are forms of quartz. Common chalcedony, agates, jaspers and chert/flint are all forms of chalcedony. All chalcedonies are the dehydration products of opal, but the sources of silica is one difference between common chalcedony as well as agates and jaspers, as opposed to chert/flint. The opals that form common chalcedony agates and jaspers derive their silica from inorganic sources such as sandstone or clays. When the source is clay they also pick up some aluminum oxide (AO). The higher the AO content the stronger and more stable the opal. Chert/flint on the other hand form from opals deriving their silica from biogenic sources such as diatomaceous earth. and is a sedimentary stone.
Opal itself starts out as a silica gel. As the silica molecules move closer and closer together, water starts getting squeezed out. When the remaining water content is 3-21% opal is the result. As the opal water content starts dropping below 3% it gains density and starts to crystallize forming in to one of the chalcedonies.
Common chalcedony comes in a wide variety of colors and patterns and can be very translucent to opaque.
Agates by definition are translucent chalcedonies with thin bands of varying colors. Many stones are still referred to as agates even though they do not fit the geological definition of agate, such as "moss agates" and "plume agates". Using names of specific stones loosely to identify any related stones is actually a common practice, but leads to a lot of confusion. For instance, when people call any unidentified copper ore "chrysocolla" or the use of the name "silicated chrysocolla" as this is not chrysocolla at all. It is a chalcedony stained by copper salts. Another is the common use of the name selenite, which is clear and non-fibrous form of gypsum, to identify satin spar that is a much more common fibrous and translucent to opaque version of gypsum.
Jaspers are an opaque version of chalcedony containing various impurities such as moganite.
Chert/flint is actually considered a type of jasper and is generally opaque although it can sometimes have a very slight translucence. Although again the word chert gets used loosely to identify some forms of chalcedony that are not really chert.
The reason I said this was sard is because is has too much translucency to be considered chert/flint. Sard is a brown colored chalcedony with more translucency than chert. I find quite a bit of sard in Southern California and Northern Nevada. The dark chocolate brown sard makes for some absolutely gorgeous cabs.
Great information. Thank you for taking the time. When I first started looking up what it could be I thought chert. After your response I looked up sard. It was much closer to what I had. I believe I do have some of the much darker chocolate brown stuff as well. It is covered by a white chalky layer though and I haven’t cut into it. There are some chips out of it and it looks dark brown on the inside. The chocolate brown stuff is in much smaller pieces. The rock in the pictures started out around 30lb before I cut it. Once I cut some of the darker stuff I will post a picture if it turns out to be that. Thanks again for the lesson.
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Post by rmf on Dec 25, 2021 18:15:52 GMT -5
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lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 25, 2021 18:27:13 GMT -5
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lorney
having dreams about rocks
Member since December 2020
Posts: 58
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Post by lorney on Dec 25, 2021 18:35:32 GMT -5
That stuff does look really similar. I am having a hard time finding information on the area I found it. Mostly just farmland. It was all over a trench that was dug down the side of a worksite. Lots of it was baked by the sun I think and seemed quite brittle. You can see in the first pics how orange it looks on the surface where it was exposed. I tried to find some bigger pieces that I figured would have good solid material on the inside.
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Post by vegasjames on Dec 25, 2021 19:12:19 GMT -5
That is really beautiful material.
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