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Hey folks,

A little background info first.

I just moved out to Arizona from the east coast and for the past few months I have been living at my house Ive noticed a large rock in the front yard. I never really looked at it and kinda put it off as well... a rock. Upon closer inspection I realized this is no ordinary rock but it someones what i would assume to be a work in progress as its polished and theres a large cut mark on the back. Im not sure if this is local to Arizona or was brought from somewhere else.

Hoping someone can help me identify this "rock" and perhaps tell me what kind of value it holds(if any).

Whatever info you guys can or cant help out with I still hope you enjoy looking at the pictures of this BEAUTIFUL rock, or whatever it may be.

Of course theres more pictures if you need them or would even like to see.

post-25117-0-40504900-1298329910_thumb.j

post-25117-0-96022500-1298330057_thumb.j

post-25117-0-86238000-1298330092_thumb.j

post-25117-0-39381000-1298330136_thumb.j

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As Bill said it might be marble, and I got to thinking maybe somebody living there before you wanted to redo the bathroom or kitchen with some home-made tiles. So my question is does anything installed inside the house look similar to the rock in question?

Just an idea.

Paul

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My guess is some type of picture jasper. Found this on internet to give you an idea what it looks like when polished.

http://www.silverstreams.com/owyheepicture.html

As you can see, there's some very close similarities. Jasper comes in many forms and qualities. Could have came from Owyhee but it has also been found at many locations in the western states. Nevada, Idaho, Oregon have produced some terrific jasper in the past.

Steve

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That looks like one of the picture jasper from Oregon. My guess would be Biggs jasper which is less valuable then Deschutes which has the deeper chocolate browns. It usually goes for about $5/lb but can be a little more of less depending on quality and size. If it has a lot of other host rock then you would need to calculate approximately how much good rock you have and adjust the price. I am in Phoenix also and could help you out determining a fare price or cut it up for you if you want. If it is a huge rock you maybe better off cutting it smaller since few people have saws big enough for the big rocks. What ever you do please do not take a sledge hammer to it or the value will be go because it will fracture.

I just did an internet search and found some nice Biggs for sale at $3/lb or $1.50/lb for orders over 100lb. A friend of mine in Mesa has a rock shop and sells hers for $2/lb. If you find that yours is very scenic then the price could be much higher. You can get the most money from slabs that have landscape scenes but cutting the rock usually cost about $1-2 per cut and you never know until it is cut what the slabs will look like. The old stock can also be a little better since the newer stuff has more pits.

Casey

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I forgot to mention that there are a several varieties of Biggs jasper. Your looks like the typical Biggs but I don’t recall if it has a more descriptive name. The one type that is very rare is Blue Biggs. It is not really blue but does have a hint of bluish brown coloring. I have seen rough sell for as much as $100/lb and I bought a single small slab last year for $35 but it had an exceptional landscape scene.

Casey

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Thank you for all the responses. I was lead to believe this was some sort of Agate (there was an old sticker on the cut side that said agate but i couldnt make out what type). I did a little research and what this to me looks like is fortification agate but I really have no idea. Im not even sure this is agate but I do know the sticker said agate on it.

Im taking it to a store in town that sells crystals and minerals and stuff like that and Im hoping they may be able to identify it.

I have more pictures I will post later on also.

Edit: I took this to the rock store and they said this is Dendrite Agate and it was the biggest solid specimen they had ever seen in one piece and could not accurately estimate the value.

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No offense but what you have is a picture jasper. Dendrites are sometimes a characteristic of picture jaspers like yours. Dendrite agate is composed mainly of dendrites and is either white ,gray and is translucent. Everything in your photos points to a picture jasper and I'll bet Casey even has the location nailed down.

Steve

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Approximately how big is this rock? It looks huge. If I were you I would make sure you don’t have anymore rocks hiding in your yard since whoever had this was definitely into lapidary. Some rocks that are no longer available can be worth a lot of money.

I would wager my paycheck on it being Biggs Picture Jasper. I have cut a lot of it and my uncle has collected it himself. If you want more opinions of identification and price you could join this web site that is strictly lapidary.

http://gemstone.smfforfree4.com/index.php?action=forum

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Kind of looks like flint that has had impurities seep in like agate. You could also probably call it jasper, seems like the term "jasper" takes in a lot of miscellaneous microcrystaline quartz rocks. Although I usually only like to refer to red jasper as being jasper.

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Kind of looks like flint that has had impurities seep in like agate. You could also probably call it jasper, seems like the term "jasper" takes in a lot of miscellaneous microcrystaline quartz rocks. Although I usually only like to refer to red jasper as being jasper.

That is how I see it. Red colors are "jasper" to me.

I have always thought jasper, agate, silaceous rhyolite, obsidian and the rest of that bunch to be volcanic.

Where marble, chert, and the rest to be metamorphic from limestone, sandstone, mudstone etc.

Am I way off base? This does not look to be volcanic glass but a metamorphic rock from an originally sedimentary formation.

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That is how I see it. Red colors are "jasper" to me.

I have always thought jasper, agate, silaceous rhyolite, obsidian and the rest of that bunch to be volcanic.

Where marble, chert, and the rest to be metamorphic from limestone, sandstone, mudstone etc.

Am I way off base? This does not look to be volcanic glass but a metamorphic rock from an originally sedimentary formation.

You are not off base. The problem is that lapidary names are usually far from accurate. The problem is lapidary rock often commands higher prices based on certain names. A few examples are Rainforest jasper which is a Rhyolite and Kambaba jasper which is petrified Stromatolite. Also if you have Onyx from Arizona it is not really Onyx yet that is what the miners will call it. Most of it is Sardonyx or even travertine. The other problem is that dealers often change the names of the rocks based on what they feel is a more marketable name leaving many names for the same rock.

Biggs jasper is a silicated mud/siltstone so by definition it is a stretch to call it a true jasper. It also goes by 6 or so variation names.

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Approximately how big is this rock? It looks huge. If I were you I would make sure you don’t have anymore rocks hiding in your yard since whoever had this was definitely into lapidary. Some rocks that are no longer available can be worth a lot of money.

I would wager my paycheck on it being Biggs Picture Jasper. I have cut a lot of it and my uncle has collected it himself. If you want more opinions of identification and price you could join this web site that is strictly lapidary.

http://gemstone.smfforfree4.com/index.php?action=forum

Its rather large, at least 60lb chunk.

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That is how I see it. Red colors are "jasper" to me.

I have always thought jasper, agate, silaceous rhyolite, obsidian and the rest of that bunch to be volcanic.

Where marble, chert, and the rest to be metamorphic from limestone, sandstone, mudstone etc.

Am I way off base? This does not look to be volcanic glass but a metamorphic rock from an originally sedimentary formation.

Bedrock Bob, no as Haderly said, that sounds right to me. Except I would say that chert or flint isn't really metamorphosed, it's still sedimentary and is just basically petrified silica rich mud. The specimen here looks like the outermost layer is actually limestone. It reminds me of some stone that can be found in Florida. Here is an extract from an article about the origin of chert in limestone,

"It is proposed that many nodular cherts in limestone have formed in the ground water of mixed meteoric-marine coastal systems where dissolution of biogenic opal and mixing of marine and fresh waters can produce waters highly supersaturated with respect to quartz and undersaturated with respect to calcite and aragonite. Aspects of cherts readily explained by this model include the observed isotopic ratios in cherts, typical field relationships, the relative resistance of dolomite to silicification, the source-of-silica problem, the preservation of siliceous fossils in cherts, and aspects of chert morphology and mineralogy".

Source: http://geology.geoscienceworld.org/cgi/content/abstract/7/6/274

Ok, just looked at the photos again, probably not a limestone exterior.

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