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Interesting rocks ?


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The first (white) one appears to be feldspar (sometimes called moonstone). The white multi-colored seems to be a mix of plagioclase and microcline feldspar, probably from a pegmatite, due to the size of the crystals. The middle one (green) is olivine, an ultra mafic rock associated with tectonics. The third one (layered or striped) I would have to look at a little closer. A silica based evaporite or hydrothermal.....jasper????

Hard to identify rocks from photos, without actually having them in your hand. But that is my stab at the first two.................

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I agree on No. 1 - Feldspar and quartz, likely from a pegmatite. Pegmatite formations are common in some parts of AZ.

On No. 2 I'd guess Idocrase, a common metamorphic mineral found in many places in Arizona and elsewhere. Sometimes called Californite or vesuvianite.

On No. 3 I guess some layered sedimentary rock, but like rluckadoo said, its hard to tell without seeing it close up in person.

Chris

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EbonBetta... Typical rocks to be found in the El Pasos... For an available source of

inexpensive "field grade" rocks and minerals, Wendi Elkins of "Minerals Unlimited"

in Ridgecrest is a good place to learn a few basic rocks that are found in the greater

area... She sells thumb sized mineral and field rock sets. Minerals Unlimited has been

in business since 1948... Wendi grew up working there with her mom and (late) dad

and has a large inventory. <www.mineralsunlimited.com> phone 760-375-5279.

All of the guesses are good... it is difficult to ID a rock or mineral in a photo. Especially

"field grade" specimens.

In much of the greater area, the principle gold deposits lie in the schist areas

that are closely connected with the granite (And granite porphyry dikes such as

in the first photo. The porphyry dikes widely vary in mineral composition. They can have

a black and white groundmass of porphyritic feldspar.)

By knowing a few rocks and their associations they can be divided into three principle

groups; such as:

(1) fault lodes: deposits in crushed schist and granite

(2) Stockworks in granite and

(3) fissure veins with more or less quartz.

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EbonBetta... Typical rocks to be found in the El Pasos... For an available source of

inexpensive "field grade" rocks and minerals, Wendi Elkins of "Minerals Unlimited"

in Ridgecrest is a good place to learn a few basic rocks that are found in the greater

area... She sells thumb sized mineral and field rock sets. Minerals Unlimited has been

in business since 1948... Wendi grew up working there with her mom and (late) dad

and has a large inventory. <www.mineralsunlimited.com> phone 760-375-5279.

All of the guesses are good... it is difficult to ID a rock or mineral in a photo. Especially

"field grade" specimens.

In much of the greater area, the principle gold deposits lie in the schist areas

that are closely connected with the granite (And granite porphyry dikes such as

in the first photo. The porphyry dikes widely vary in mineral composition. They can have

a black and white groundmass of porphyritic feldspar.)

By knowing a few rocks and their associations they can be divided into three principle

groups; such as:

(1) fault lodes: deposits in crushed schist and granite

(2) Stockworks in granite and

(3) fissure veins with more or less quartz.

Yesterday, searching "El Paso Fault", I found and read, "Field Guide to the Geology of Red Rock Canyon and the Southern El Paso Mountains, Mojave Desert, CA" which discusses the state park and the surrounding geology,

Link to .pdf: http://www.nhm.org/expeditions/rrc/documen..._fieldguide.pdf

a worthwhile read, I felt, as the area is in my plans.

Jim Straight, please lift my ignorance and inform me about 'stockworks'. Thanks.

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Gosh... I'm just a slow two finger typest... However, Knowitall2be, I'm impressed

with your thirst for knowledge... I'm very limited in my computor savvy. I cannot

even open a PDf file. I'm just one small step above the old typewriter with a ribbon.

Stockwork: I will try to give a simple basic definition; It is a mass of rock irregularily

fractured along which mineralization has spread. Basically the ore is usually

disseminated throughout the fractured areas so the larger mass may be economically

mined as a whole. Now there other terms, such as "oreshoots," and we could now

write a book.

I believe some of the motherlode mines, such as the 16 to 1 are in stockworks

and possibly in oreshoots. Hopefully Reno Chris will be back to answer any questions.

In the meantime, keep in mind the greater geology of the Randsburg-El Paso-Summit

district within the Mojave desert is complex. It is still being studied by undergraduate

students as their thesis... There is a Tertiary Channel... Tungsten hardrock and placer,

Hardrock gold and placer. Hardrock silver mineralization... Plutonic and volcanic rocks,

Sediments and Metamorphic rocks...

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Gosh... I'm just a slow two finger typest... However, Knowitall2be, I'm impressed

with your thirst for knowledge... I'm very limited in my computor savvy. I cannot

even open a PDf file. I'm just one small step above the old typewriter with a ribbon.

Stockwork: I will try to give a simple basic definition; It is a mass of rock irregularily

fractured along which mineralization has spread. Basically the ore is usually

disseminated throughout the fractured areas so the larger mass may be economically

mined as a whole. Now there other terms, such as "oreshoots," and we could now

write a book.

I believe some of the motherlode mines, such as the 16 to 1 are in stockworks

and possibly in oreshoots. Hopefully Reno Chris will be back to answer any questions.

In the meantime, keep in mind the greater geology of the Randsburg-El Paso-Summit

district within the Mojave desert is complex. It is still being studied by undergraduate

students as their thesis... There is a Tertiary Channel... Tungsten hardrock and placer,

Hardrock gold and placer. Hardrock silver mineralization... Plutonic and volcanic rocks,

Sediments and Metamorphic rocks...

Jim, it does not matter how many fingers one uses to type, how well one spells or uses grammar. That you and others here so willingly share the gold of knowledge is what matters. Thank you so very much for that. Because of my already acquired knowledge I realize that I have such a small amount I will never knowitall and my fate is to continue as a 2b. Hey, fate could be a lot worse.

I look forward to acquiring a copy of the book you have written. I am hopeful that Bill gets or has some in stock so it is no more distant in my future than the arrival of a back-ordered detector.

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I'm really kind of curious which green rocks Mr Straight meant when he sqaid he slowed down when he saw them. I'm in town but I plan to be back out looking in a couple of weeks.

See the thread Patch Hunting 101. Jim just incidentally answered it there.

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See the thread Patch Hunting 101. Jim just incidentally answered it there.

Oops, that was Denny who answered that question in the thread Patch Hunting 101. Please excuse my error.

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Oops, that was Denny who answered that question in the thread Patch Hunting 101. Please excuse my error.

FWIW I decided to go to Wikipedia where I looked up breccia. It was a very informative read which I recommend. I'm gonna go back and read up on schist and olivine.

Also I want to comment on the third rock. As (among other things) a graduate gemologist I agree with the geologists/prospectors who have commented that one cannot make reliable identities from pictures or just by holding a rock/stone/specimen. However one identifier which is considered in gemology is the fracture. From the image there appears to be a couple of similar fractures which are in two distinct directions to each other, one of which appears to produce a well defined (sharp) surface edge. To my training this suggests micro- or crypto-crystaline structure, but considering I have only the image to go by that conclusion cannot be relied upon as a guide to identity.

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Is there any chance the third rock is banded obsidian? Regular obsidian has conchoidal (glassy) fracture but I do not know about the banded variety. I agree with the others that identifying a rock with just a picture is hard. Some things that might help the experts (and I am NOT one of those!) are: How heavy is the rock (does it feel lighter or heavier for its size)?, Does the surface feel smooth or rough?, What happens when you hit the edge with a hammer? Geologists seem to always carry a magnifier around with them. Somehow it helps them to determine what the rock is. I'm guessing that they are looking at the crystal structure.

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