The mineral which lies in his land consists of earth and dry substance, far more rich than any water can be, whereof he has sent as much as the bearer can carry, less than he wished for a perfect trial. The place is rich in this stuff, for in heat of summer copperas grows in the chinks of the rocks which cover the mineral. There is in the mine great store of brimstone. It may be digged at a small charge and lies within two bow shots of a navigable river which, within 7 miles empties itself into the sea, and will bear a bottom of 20 tons. Turf and 'pett' [peat] is to be had for boiling, within half a mile of the mine. Divers perfect trials have been made out of alum and copperas, both in the country and in London . The copperas would not quit cost. Skill is wanted to destroy the copperas and to make a greater quantity of alum. If there can be found a man of skill, no doubt the thing is infinitely rich, being a commodity that England so much uses in the dyeing of clothes, and which they are fain to procure out of Italy, and is commonly worth 40 marks or more the ton. For Sir John's part, finding such uncertainty in alchemy, he never durst adventure so great a work himself, and was not willing to part with his commodity without a part, though divers times offered a great rent. Hopes his Lordship will use him honourably and he shall not find Sir John difficult to come to any reason if it pleases God to reveal the knowledge and secret to the trier. It seems that Sir John is the first finder thereof. Porphyry and speckled marble of white and red are in that hill not far from the mine, but there are none here who have skill to polish the same. The rest of this letter, which concerns the transmutation of iron into copper by a process which Sir John professes to have forgotten, is printed in History of the Gwydir Family (1878 ed.), p. ix, no. 2. Overleaf is a rough draft of Sir John's letter (see no. 471 in the printed Calendar of Wynn(of Gwydir) Papers (NLW, 1926)) also printed in the same work. See also no. 470 in the printed Calendar of Wynn(of Gwydir) Papers (NLW, 1926).