Thank you It's pen and ink on bristol paper. To be more specific, it is a turquoise Platinum Procyon F fountainpen filled with Platinum Carbon black ink on Canson XL Bristol paper
Edit: I'm a fountainpen guy. My real treasure is a Mabie Todd Swan from the 1920's. I have not done a drawing with yet, since I do not dare fill it with pigmented / waterproof and lightfast ink. But I will have to give it a try one day.