[Rockhounds] Opals from Africa

[friedmanhvj at yahoo.com]

Hi rockhounds,

I am not a rockhound myself (rather a paleontologist) so, I don't know much about gems. I have a question: recently I went to a estate sale, in which there were all kind of rocks on tables and in cabinets. I found in one of these cabinets at a corner a small container unlabeled with which appear to contain an opal in matrix. It is very similiar to the opals tat I have seen in gem and mineral shows. I think they come from Eritrea or Ethiopia ? The matrix is pinkish and chalky looking. The opal has an amorphous shape. It is rather small, but I have seen them priced highly in the above mentioned shows. My question is, where can I get more info on opals coming from that part of the world and also,  are there lab made opals? I pay only 50 cents for this one. It looks so much like the ones sold at gem and mineral shows.
I have an opalized brachiopod from Australia and I remember that it was rather pricey.

Any info about opals from Ethiopia or Eritrea? would be greatly appreciated. 

Thanks.

Virginia Friedman