UPDATE:
First I appreciate all the suggestions that have been offered. I read each and every one and considered them all carefully.
After yet another (nearly) sleepless night pondering this dilemma, this morning I decided to test the old dictum "The Enemy Of Good Is Better." So I went to the garage, strapped a headlamp on my forehead, procured a pair of fine-tipped forceps, and pulled the little glass shard out of the tire. It was a small bugger, about the size of a wooden toothpick head. As soon as I removed it there was a hiss of white liquid air- sealant. This did not stop. I attached the pump and kept re-filling the tire to a pressure of about 30 PSI, while orienting the puncture side down so that the sealant inside would pool over the hole and (I hoped) plug it. But the hissing and bubbling continued. For about five minutes, Then it stopped. I pumped the tire up to 50 PSI (My riding pressure) and the leak resumed, but only for a minute or so.
It's been three hours and on repeated pressure checks the tire has remained at 50 PSI.
I am looking for some SuperGlue to instill into the tiny crack in the rubber.
Tonight, I will sleep well.
Thank you.