Glittery stone necklace

This necklace I have no clue about, only that I got it about 2 months ago at a family run estate sale. One stone broke and still on necklace, any ideas ?

Thanks

Billy D.

 

Opal - Onyx?

 

White ones are quartz, I can't make out the black ones. Has a bit of age, given the cotton thread and that screw clasp.

 

White stones look like quartz (silica). I have similar necklace. Unfortunately, cannot show you a photo, I have technical problem with uploading files.

Natasha

 

I would like them to be opal better, oh well. Quartz silica, I will research that too.
Thanks Rayo56 , Ownedbybear and Natasha.

 

Those actually look like glass from here. The holes where the string goes through are a dead giveaway. They're rounded - i.e. molded. Stone beads would have sharper edges. The string and 30s barrel clasp and seed beads make me pretty well certain.

 

Glass, okay I'll go with that.