plehbah, excellent question on color and category, we just call it olive or olive green, it's not awfully dark. I don't know if this is considered black glass or not (comments needed by Harry Pristis). MichaelB, a pic of the pontil would be icing on the cake.
Federal Bureau of Governmental Redundancy Reduction Agency
From: "Bill Lindsey
Bureau of Land Management (retired) - Klamath Falls, Oregon"
"A pontil mark is a variable size and type of scar left on the base of a bottle by a pontil rod. A typical pontil rod or "punte" was a long (4-6 feet) rod which was securely attached to the base of the just blown hot bottle. The rod had to be long enough so that the heat transference from the extremely hot (2000°+ F.) bottle did not reach the hands of the pontil rod holder. A pontil rod held the bottle during the steps in the bottle blowing process where the blowpipe is removed (cracked-off) from the bottle and that break-off point is "finished", i.e. the lip or finish is completed. Once the bottle is "finished", the pontil rod is sharply tapped which breaks it free of the bottle. The base of a bottle which was held with a pontil rod will almost always retain some evidence of the pontil rod attachment."
"It's a quest. It's a quest for fun, I'm gonna have fun and you're gonna have fun, we're all gonna have so much #!@*^& fun we'll need plastic surgery to remove our %$#@ smiles!" - Clark Griswold, National Lampoon's 'Family Vacation'.
From: "Bill Lindsey
Bureau of Land Management (retired) - Klamath Falls, Oregon"
"A pontil mark is a variable size and type of scar left on the base of a bottle by a pontil rod. A typical pontil rod or "punte" was a long (4-6 feet) rod which was securely attached to the base of the just blown hot bottle. The rod had to be long enough so that the heat transference from the extremely hot (2000°+ F.) bottle did not reach the hands of the pontil rod holder. A pontil rod held the bottle during the steps in the bottle blowing process where the blowpipe is removed (cracked-off) from the bottle and that break-off point is "finished", i.e. the lip or finish is completed. Once the bottle is "finished", the pontil rod is sharply tapped which breaks it free of the bottle. The base of a bottle which was held with a pontil rod will almost always retain some evidence of the pontil rod attachment."