I hear you there about the shells. I live in Orlando and go to Clearwater or Smyrna all the time. Where about in South Fl do you live if you don't mind me asking?
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I am a trained non-practicing calligrapher and I think this is what jimmy is referring to.
The ink stick is rubbed on the slate stone with water and is then applied to the paper with brush, pen or quill.
Yup, that is the stuff. Made ink to apply into skin with that gizmo.
I've tried the slate and it was a waste of time. YMMV. I also tried a suzuri used in making ink for Japanese calligraphy. The one I have is from a mountain in Tokyo IIRC ........ no good action there either. I am going to go rock hounding though. Living in South FL all I've come up with is sea shells. So far none of them make a good slurry but I'm going to keep trying ......
Rockhounding in S Florida is an oxymoron. Everything is Calcium Carbonate unless you dig down several thousand feet and then you'll need pumps big time.