Looks like slag glass at the bottom, into those lines and into that lava-like surface near the top... I can find no maker mark on this lamp... Only identifying clue is the Honi Chilo on the harp which I believe only represents the maker of the harp. No matter, it's a true period beautiful piece of Mid-Century Art Glass and Lighting.
38 Tall from table to top of heavy brass acorn finial. It sits on a 4.5 cube of painted black metal. As you can see there is some chipping of the paint on that metal, which is the only flaw to this lamp. The glass portion is about 18, and it has a 3-Way Twist Switch. If interested in purchasing one, I have a black linen 18" round x 10" high shade on it for these pictures.
I think it's perfect for it, but you can choose to your liking. As is demonstrated by the pictures. This item is in the category "Collectibles\Lamps, Lighting\Lamps". The seller is "livingmodesign" and is located in this country: US. This item can be shipped to United States.