Contax RTS II Focusing Screen

Does anyone know what the focusing screen on an RTS II is made of?

While reinstalling mine after cleaning, the plastic tip of my blower bulb scratched against it and left a streak much worse than the dust that was there before. Further cleaning with soapy water failed, as did a gentle rubbing with a soft, clean sponge. Either the screen is scratched (unlikely given how soft the nib of the blower is), or plastic material has embedded itself in the screen. If it is plastic embedded in the screen, then acetone might be able to dissolve it away - which will only work if the screen is made of glass.

Anyone know?

Or, does anyone have a Contax FS-1 or FS-2 for sale?

I'd suspect plastic and keep the acetone in the bottle.. I've been wrong before though.

Pretty much all SLR focusing screens are plastic. Soft plastic. Even a soft blower nozzle could deform the plastic.

Yep, looks like it is plastic, which explains how the blower tip did that damage. Quite the bummer.