Joined: Sat May 21, 2011 7:09 am Posts: 77 Location: Italy
Hi.
I have this stone:
It is 28x9,5x9 mm and 3,46 g weight, opaque. Maybe it comes from Pakistan (not sure). Under UV 366 nm it becomes more red. Weak magnetic attraction. The shape is tipical of corundum. I try to define the S.G.: it is about 3,31, out of range of corundum, but there are many holes filled of dust (and air bubbles when immersed in water).
The corundum falls in position 9 of Moss scale: what kind of "termites" causing these holes? Are these holes normal in corundum ? (Or better, could be this stone a corundum?)
Joined: Thu Dec 13, 2007 3:42 pm Posts: 4091 Location: the Netherlands
Hi,
It's definitely a bit of corundum. The holes may either represent different crystals that once lived in and around the crystal but were dissolved somewhere along the line or areas of lesser stability which have been dissolved over time... The dissolving factor may have been acids or magma... often a bit of corundum traveled a violent road to the surface of the earth.
Joined: Fri Apr 12, 2013 5:54 am Posts: 12 Location: Far North QLD
I have seen this in certain types of metamorphic Corundum and consider it to be a result of a relatively low temperature and pressure during formation.
Attachment:
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Joined: Thu May 03, 2007 1:19 am Posts: 370 Location: Pakistan
If the specimen is from Pakistan then the holes might be a result of an acid bath which at times dealers give to pieces overly penetrated by calcite which dissolves away leaving behind cavities. Practice of acid treatment is on the decline though because it leaves behind both dealer and the specimen in an unhappy state.
Joined: Sat May 21, 2011 7:09 am Posts: 77 Location: Italy
Hello mrb,
thanks for your opinion: the sample comes from Sri Lanka and, when I put it for the first time in water, this corundum has released a strange uncolored oil-like substance (may be the acid).
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