Emily Dickinson Lexicon

SHA-GREEN, n.¹ [Pers. سغري sagri, the skin of a horse or an ass, &c. dressed.]

A kind of grained leather prepared of the skin of a fish, a species of Squalus. To prepare it, the skin is stretched and covered with mustard-seed, which is bruised upon it. The skin is then exposed to the weather for some days, and afterward tanned. – Encyc.