a sombre runic book

This book is bound in very old leather dyed black as soot. Flowing, sinuous, lead-grey letters adorn the cover. The style is ancient, and the craftsmanship unheard of in this age. |^ | ^ < (|||)) (||))|)_n |/| || / It teaches old secrets about potions and magic. To examine it, hold it and read it.

It is a sombre runic book.
It weighs four pounds.

You identify a sombre runic book.
It is an unsellable object.
It weighs four pounds and seven ounces, and it is worth about one lauren and one celeb.
Its keywords are book, sombre, runic, and formula.