This piece is in the collection of a friend and has been for several decades. When he purchased it, it was said to have been an experiemental Hartford Faience Co. insulator. There was another insulator exactly like this but it was heavily damaged. I'd imagine these both surfaced in the 1970s or 1980s at a show in/around Connecticut.

The insulator itself is very heavy for its size. When tapped, it sounds like porcelain but the weight is deceiving. Some have suggested it may be produced of bisque with a transparent glaze but I haven't the slightest clue. I do know that the shape is one of the most intriguing things I have ever seen.

UPDATE: Rick Soller was kind enough to help out. It seems that this was an experimental piece produced by McGraw-Edison and is made out of teflon and alumina!

Be sure to check out Crown Jewels of the Wire:

http://cjow.com/archive/article.php?month=1&a=01Out%20Of%20The%20Frying%20Pan%20Onto%20The%20Wire.htm&year=1971

http://cjow.com/archive/article.php?month=2&a=02Porcelain%20Insulator%20News.htm&year=1973

Thank you Rick!