More on suzuri from Tankei.

When I was trying to find out more about Tankei suzuri (and who wrote Cさん's poem), I found this interesting rendition from a blog based in Shitamachi:

The writer includes the following by way of explanation:

上記、句に出てくる「端渓（たんけい）」は硯の材料として有名な石の名前です。
中国広東省肇慶市に端渓という川があり、その両岸から産出されるのだとか。
きめ細かくしっとりとみずみずしいのが特徴なんだそうです。。。。
The "Tankei" that appears in the poem above is the name of a kind of stone that's famous for use in suzuri. It comes from the banks of a river called Tankei, near Zhaoqing, Canton (Guangdong), China. It's said to be known for its fine, soft, smooth grain.

Cさん　e-mailed today that 先生 said the "hada" in question is more likely the surface of the suzuri (which now sounds like it may have the feel of skin), and that seems to work with the "ni" construction. Probably, then, too, would be better to read "komakai" as referring to the fineness of the grain, rather than to a small inkstone.