Well Sir, the story the seller was telling was that these were alleys packaged by ravenswood. he told me the story of speaking to the lady who put them in the bags herself. But my being of lesser marble smarts than most, I seen an old friend, who needs to stay out of my neck of the woods, Mr. Sheppard. I asked him about the story and he and Mr. Powell, I believe that is his name, told me that they were alley. When MK bought alley in St marys they had alley stock and MK bags. so poof! they had alley mibs in mk bags. I hope this is satisfying. When Ron and The president of the marble club, I think, told me what they were I took it as set in stone and good enough for me.
P.S. I have no knowledge of the glass mix or adventurine issue. Plus If I say Jabo 3 times in a mirror with the lights out she will appear so i mustn't speak further.