Identify my rocks of interest.

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aussiefarmer

aussiefarmer

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Sorry about poor photos, The first rock appears black maybe a little blueish , It has a glassy look where it has chipped off , it has a reasonable weight for its size , its non magnetic , light seems to enter it slightly maybe but does not illuminate it or pass through it ??

1439018177_rock_chop.jpg


1439018232_chop_rock.jpg


The second mystery is what I think is one of the forms of fools gold ,its not as impressive in photos , it is shinny silvery gold in color , its in a cement like base which must have been liquid moving between the quarts and slate , I have in the past seen it on its own speckled through quarts , seems hard doesn't melt with blow lamp ??

1439019277_fools_gold.jpg


1439019528_foolsgold.jpg


Thanks in advance for any ideas.
 
Hey aussiefarmer, I think the first sample vis probably Obsidian from the discription you gave and the picture. 2nd sample might be Pyrite in it's host rock or Arsenopyrite or another type such as Chalchopyrite. Are the gold bits cubic? If so it's Pyrite, which sometimes can contain gold in the Sulphide, Pyrite is Iron Sulphide.

More experienced rock hounds may have a better Idea.
 
I thought it might be obsidian , correct me if I am wrong but obsidian is generally found where sapphire's are ?

The second sample has many shapes and what I have believed to be pyrite in the past is flatter with sharp corners where as this is more random in shape and surface .

Saying that its only a uneducated guess that it was pirate I have found in the past it was flat shinny sharp corners and would chip or shatter when scratched.

Very interesting thanks for the feed back Heatho . https://www.prospectingaustralia.com/forum/plugins/ezbbc/style/smilies/big_smile.png

Now I have mastered putting photos up I will be able to play show and tell from now on .lol.
 
No worries mate.

There are quite a few types of Pyrite, and I'm pretty sure most will chip or shatter when something harder hits or scratches it. Obsidian is basically lava which has cooled very quickly where crystals have not had time to form.

I'm not sure about the relationship between Obsidian and Sapphire to be honest, they both come from volcanoes but I think that's where the relationship ends. Generally in my reseaching sapphire you need an area that is high in Aluminium mineralisation as sapphire is Aluminium Oxide.

If you can share your general location in this thread or via PM I can let you know from the maps I use if you are close to any Sapphire deposits.

If you're near Inverell, Glen Innes, Oberon, Crookwell, Gulgong, Bingara, Barrington Tops or Nundle then there may be a good chance of Sapphire and/or Diamonds nearby. :)
 
The first specimen does look like obsidian aussiefarmer. There's a similar looking stone sometimes associated with garnet-bearing areas called Hornblende or Amphibole. It's also black or even blue-black and glassy looking. I cabochoned a piece once and if you like black stones I reckon it would look great set in jewellery, it takes on an absolutely brilliant polish.

Have a good scratch around your place where you found those specimens, you never know what else might turn up. I have seen obsidian turn up on the sapphire fields but I'm not sure that the presence of one necessarily implies that both are present. But it sounds like your place saw some ancient volcanic activity - if I were you I would be up there with pick, shovel and sieve, something very interesting might well be hiding in the ground.
 
How big is the black stone?
It looks like a blackjack spinel to me (try googling it to compare).

If it is, then yes it is usually associated with sapphires.
 
Yes it could be spinel as well, or possibly a number of other things.

The black spinel from my field has an extremely fine but distinct "texture" to the surface, as though it has been painted with chalkboard paint. I don't know if it's like that elsewhere.

If you have a local lapidary club, take it down there and let them examine it. Photos can't always give a definitive answer.
 
If it's Spinel there will be no light entering it at all, in my opinion of course. "light seems to enter it slightly maybe", that's the part of AF discription that made say it wasnt Spinel/Pleonaste.

SG test would give a much better chance of propper identification on it.
 
Heatho said:
If it's Spinel there will be no light entering it at all, in my opinion of course. "light seems to enter it slightly maybe", that's the part of AF discription that made say it wasnt Spinel/Pleonaste.

SG test would give a much better chance of propper identification on it.
Click to expand...

SG test ?? I am a uneducated rock hopper mate
 
Yep found easy instructions for SG test thanks .

Things You'll Need

V

Beaker

V

Water

V

Scale

Instructions

1.Fill the beaker halfway with water. Note the level of the water.

2.Put the mineral into the beaker. Make sure it fully submerges in the water.

3.Note the level of the water once again.

4.Calculate the difference in the amount of water before the mineral was put in and after it was put in.

5.Spill out the water from the beaker.

6.Weigh the empty beaker.

7.Fill the beaker with the amount of water the mineral displaced (calculated in Step 4).

8.Weigh the beaker with the water.

9.Subtract the weight of the empty beaker from the weight of the beaker calculated in Step 8. This is the weight of the water displaced by the mineral. Accordingly, it has the same volume as the mineral.

10.Weigh the mineral.

11.Divide the weight of the mineral by the weight of the water it displaced. This will be the specific gravity of the mineral.



Read more : http://www.ehow.com/how_7553163_test-specific-gravity.html
 
Hey guys, the second picture looks like a bit of Pyrite, Chalcopyrite and Pyrrhotite. Pyrrhotite is an iron sulfide as well and has that typical metallic brown colour to it. It's usually found with chalcopyrite. It's extremely hard to tell with the second photo however that dark purple brownish-black alongside the rusty red brown mineral staining are just different Iron oxides (looks like limonite and ilmenite) which are found associated with pyrite-chalcopyrite bearing rocks. I don't think theres a major content of Arsenopyrite and if there is it isn't visible in this particular sample. If you do stumble upon some arsenopyrite though it's a good sign that there might be gold in the region as arsenic minerals are indicative of mesothermal and epithermal type deposits.
 
geosam said:
Hey guys, the second picture looks like a bit of Pyrite, Chalcopyrite and Pyrrhotite. Pyrrhotite is an iron sulfide as well and has that typical metallic brown colour to it. It's usually found with chalcopyrite. It's extremely hard to tell with the second photo however that dark purple brownish-black alongside the rusty red brown mineral staining are just different Iron oxides which are found associated with pyrite-chalcopyrite bearing rocks. I don't think theres a major content of Arsenopyrite and if there is it isn't visible in this particular sample. If you do stumble upon some arsenopyrite though it's a good sign that there might be gold in the region as arsenic minerals are indicative of mesothermal and epithermal type deposits.
Click to expand...
Top comment mate and welcome :)
 
No worries mate, I think it's a good find :) It might even be worth doing some exploring around the area. I bumped into a few samples exactly like that and ended up discovering a nugget :)
With the black stone I would say it has a strong chance of being a sapphire. Many sapphires are black and the conchoidal fracturing is indicative of it :)
 
Sam, I am almost 100% positive it's not a Sapphire, a simple SG test would prove this as there is a vast difference between Sapphire and Obsidian SG.

Both can have a conchoidal fracture but that's where the similarities end. I've seen a lot of Sapphires and that really does not resemble any I've seen.
 

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