kelbro
Alfred Spatchcock
I'm sorry it was Amazon and they don't actually say Tsushima. I learned of it from another razor forum and from a YouTube video. There is a larger stone available at Amazon as well.
https://www.amazon.com/gp/product/B01AOMD7C6/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
They do say it in the description but they use 'near' to disclaim it. That's professional marketing.
- Quarried from a now closed underwater mine near South Tsushima Island, Japan; golden stamp of authenticity; very limited stock