<p>This is the classic description of a porphyry copper-molybdenum deposit.</p>
<p>What happens is that there is a magmatic intrusion (the porphyry), which then solidifies. When it solidifies, it expels acidic hydrothermal fluids which carry metals in them - most often copper (represented by chalcopyrite) but also sometimes molybdenum (represented by molybdenite).</p>
<p>Once the fluids hit solid rocks, they react with it, and become neutralised. The carrying capacity of the fluids diminish, and they deposit the metals into the minerals you observe. The solid rocks can be pretty much anything. It can be the porphyry itself, another porphyry that happened to be around, sedimentary rocks, or whatever.</p>

CC BY-SA 4.0
2021-03-24T12:43:34.930Z
2021-03-24T12:43:34.930Z
Gimelist
<p>What type of ore deposit does this rock best represent?</p>
<blockquote>
<p>A rock with a porphyritic texture is cross cut by a stockwork of
quartz veins.  Bordering the veins is extensive alteration of the host
rock. The vein contains fine-grained (~1mm) chalcopyrite and
molybdenite.</p>
</blockquote>
<p>I believe it to be a hydrothermal ore deposit as porphyry ore formation, stockwork and the Cu-Mo-Au element list indicates.</p>
<p>Is this a correct line of thinking and if so is it specific enough, do you think?</p>

CC BY-SA 4.0
2021-03-16T14:08:21.053Z
Is this simply a hydrothermal - porphyry - type ore deposit?
Edward
CC BY-SA 4.0
2021-03-16T14:49:41.297Z
I could be wrong, but sounds a bit like a homework question because of the way you word it?  If so, you'll need to provide some thoughts at least to show what you're thinking and that you're making a reasonable effort, as Stack Exchange doesn't exist just to feed homework answers :-)
JeopardyTempest
CC BY-SA 4.0
2021-03-16T15:02:50.220Z
It is indeed, however, per my comment above, I am meerly seeking confirmation that it is simply a hydrothermal ore deposit @JeopardyTempest
Edward
CC BY-SA 4.0
2021-03-16T15:07:26.947Z
It'd be good to put that in the question itself... and a short thought on why you go in that direction :-)
JeopardyTempest
CC BY-SA 4.0
2021-03-16T15:12:33.730Z
@JeopardyTempest Amended I believe :-) , do let me know if there is anything else as I am very new to this site.
Edward
CC BY-SA 4.0
2021-03-16T15:45:51.123Z
Looks good, hope you get a good response, and that you can find places to contribute as well! :-)
JeopardyTempest
<geology><mineralogy><rocks><minerals><economic-geology>
Ore Deposit Identification
Edward
# Ore Deposit Identification

(Asked by: username_0 on 2021-03-16)

What type of ore deposit does this rock best represent?

> A rock with a porphyritic texture is cross cut by a stockwork of
> quartz veins. Bordering the veins is extensive alteration of the host
> rock. The vein contains fine-grained (~1mm) chalcopyrite and
> molybdenite.

I believe it to be a hydrothermal ore deposit as porphyry ore formation, stockwork and the Cu-Mo-Au element list indicates.

Is this a correct line of thinking and if so is it specific enough, do you think?

**Tags:** geology, mineralogy, rocks, minerals, economic-geology

> **Comments:**
> **username_0**: Is this simply a hydrothermal - porphyry - type ore deposit?  
> **username_1**: I could be wrong, but sounds a bit like a homework question because of the way you word it?  If so, you'll need to provide some thoughts at least to show what you're thinking and that you're making a reasonable effort, as Stack Exchange doesn't exist just to feed homework answers :-)  
> **username_0**: It is indeed, however, per my comment above, I am meerly seeking confirmation that it is simply a hydrothermal ore deposit @username_1  
> **username_1**: It'd be good to put that in the question itself... and a short thought on why you go in that direction :-)  
> **username_0**: @username_1 Amended I believe :-) , do let me know if there is anything else as I am very new to this site.  
> **username_1**: Looks good, hope you get a good response, and that you can find places to contribute as well! :-)  

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## 1 answers

### Answer by username_2 on 2021-03-24. Score: 2 | Accepted answer

This is the classic description of a porphyry copper-molybdenum deposit.

What happens is that there is a magmatic intrusion (the porphyry), which then solidifies. When it solidifies, it expels acidic hydrothermal fluids which carry metals in them - most often copper (represented by chalcopyrite) but also sometimes molybdenum (represented by molybdenite).

Once the fluids hit solid rocks, they react with it, and become neutralised. The carrying capacity of the fluids diminish, and they deposit the metals into the minerals you observe. The solid rocks can be pretty much anything. It can be the porphyry itself, another porphyry that happened to be around, sedimentary rocks, or whatever.


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