FMF - Friends of Minerals Forum, discussion and message board

[CornelDumitru]

Hi, this is my first post here. Please help me identify this rock.
I have the specimen from a person who found it in the general area of south-west Romania.
The area is known for beauties like andradite garnet (Dognecea).
So I will see how many pics I can post, but here are the specifics:
Largest dimension is 13 cm.
Mass 883 grams, volume ~ 300 cubic cm, SG 2.95
Hardness ~6.
Full opaque, no translucent part.
Streak (see photo).
The "crust" ( I call that the contact area that looks weathered, or melted as I suspected at one moment) leaves a dark streak.
The main material (I call it "inside", the olive green luscious material) leaves no streak (that I can see). Or may be white.
Reaction to magnet. The "crust" will attract the magnet ( I have a video). The general material will not.
Reaction to LWUV. None.
Reaction to table vinegar. None on the interior (no effervescence, no bubbles). It dissolves and wash out some small dark particles from the crust.
The crust may have been in contact with pyrite, I can see particles with the loupe.
The main material has many inclusions like short black wires. And spherules of something. Manganese ?
The general appearance as uniform colour (olive green) is intriguing. It may not be a showcase specimen but the overall intensity and uniformity of the colour are special, IMO.
It does not look like sedimentary rock to me.
But crystal habit is not clear either. There are thin lamellae and some repeating angles, I hope the pics will show it.
Now on to the pics.

[Kevin Schofield]

[CornelDumitru]

[Pete Modreski]

Cornel, I quite agree with Kevin, about this being most likely a piece of some kind of furnace slag; for all the reasons that he states. But my compliments, too, for your doing such a good job of describing the properties of the specimen--the hardness, etc.

To add one extra comment, as Kevin asked, this shows how it really is very useful--to those to whom you might be showing a specimen, to help identify what it is--to describe more specifically, where it is from. And not just "where", even the exact geographic location, but what sort of site it was found at; whether at a rock quarry, an old mine dump or mining prospect pit, an industrial site, a roadcut (through X kind of rock), a stream bed, a beach, a mountain top, etc. The more that one is informed about what sort of place the specimen was found at, the more one can be guided to give better suggestions of what it is!

[Pete Richards]

The second and third photos from the end show black spheroids which probably are droplets of the metal being smelted. It might be interesting to test these with a small, powerful magnet. You can hang one from a fine thread and bring the specimen close to it and watch for the magnet to deflect towards the specimen - that's much more sensitive than trying to tell by how it feels when you bring a magnet to the specimen.

[SteveB]

+100 to the posts on you providing exactly the sort of "what is this" post information that is requested. Too many people don't put any effort into letting us help them.

My gut is also glassy slag of some form. Many garbage dumps/land fills used to be burnt in order to reduce it down to allow for more dumping on the same site. Its possible this was a result of such. It could possibly be Roman in origin as they built smelters all over Europe as they expanded their empire. Or it could just be plain modern industrial furnace waste. If you had an accurate location point that would provide the extra research aspect to follow (many people think they have found something rare and valuable and so don't disclose the location so you're on your own really). As its not a natural mineral this forum can't help much further. A spectroscopic analysis of a piece may give you a clue as to what its waste from. It may be from glass maker or smelting a specific metal. If its roman it could indicate a location where a buried hoarde may be as furnaces take time to build and during the encampment treasures were often buried in deity offerings for success when they disembarked. All of those option require further testing and research of the source site precisely (country, town, region not good enough) and then find groups researching that subject in that region. If its roman it could have historical value but only if its found location is known (to the meter preferably) so it can become a data point on a map helping archeologists with their efforts.

cheers Steve