Black Glass

Yes.  Blenko did produce Ebony glass.   Many West Virginia Glass makers had ebony in their lines.
May I suggest you visit the American Glass Museum located in Weston - formerly the WV Glass Museum.
From your Clarksburg location it's a less than 30 minute drive.   There you'll find books with all the Ebony Glass made in West Virginia.  HJH

Blenko Ebony