226 ON THE DETRITAL TIN-ORE OF CORNWALL. 
parts of the district; but most frequently, though not always,* 
towards its southern boundary; there is, however, reason to 
believe that such discoveries have been of late much less numerous 
“When the lump was broke it appeared to consist of two incrustations sur- 
“rounding the whole, and a Nucleus or central substance of crystal intermixed 
“with the purest malleable tin. The outmost crust was about the 8th of an 
‘inch thick at a medium, and of a brownish straw-colour; the 2nd incrustation 
‘‘was more blackish in colour, closer grain’d with some faintish appearances 
‘“‘of whitish specks interspersed, about one third of an inch thick; these 
“two incrustations...inclosed a third substance, consisting of laminated crys- 
‘‘tals, rising side by side out of an edging shining like melted tin, which 
‘lies as it were at their roots coherent to the 2nd incrustation; the Lamine 
“of crystal...being shot in a great variety of directions intersect each other, 
“and leave a vast number of cells, within which are plainly seen, and may 
“be freely cut with a knife, many specks and granules of perfect native tin.” 
Boruase, Journal of the Royal Institution of Cornwall, i, (No. iv.) Supple- 
ment, p. 25. 
“On...the 27th of July ’65 was found in a Stream-work near the borough 
‘‘of Granpont,...another lump of the same kind of Tin-ore as the former, 
‘as to its crust and covering; its weight was between eleven and twelve 
“pounds ; the pure tin was not in granules as in yé first Specimen, nor thin 
‘Cas a leaf as in No. 2, but much more abundant, and in some places more 
“than one inch thick; the Metal was inclos’d so securely, that but for the 
“ extraordinary weight it had pass’d unnotic’d....but whether Native, or 
“Tin melted by Art and inclosed by long lying in a petrifying Tin-water with 
‘‘a Crust similar to that of the foremention’d SISSON I can’t affirm.” 
Ibid, p. 26. 
Some few years ago a mass of Jew’s-house tin, which weighed seventy 
five pounds, was discovered at Burngullow in St. Mewan. Its shape was 
rather oval, and it measured— 
20. inches in length ;— 
ial. me width ;— 
and at the middle 2:5 5 extreme thickness; thinning, how- 
ever,—almost to an edge—at the sides and ends. The discoverers took it to, 
and sold it at, Calenick Smelting-house near Truro, and there it still remains. 
Mr. Francis Mice, of Calenick, MSS. 
A mass, in which small, rich, pebbles of stream-tin-ore and fragments of 
charcoal were cemented by metallic tin, was discovered, immediately below 
the surface, in Trethowel-wood near St. Austell. Occasional interstices 
between the other ingredients, were sometimes thinly encrusted with light- 
lemon coloured granules. Its weight was eighty pounds; and—about three 
years ago—it was sold to the Carvedras Smelting Company (at a rate of £95 
per ton,) for £3. 6s. 5d. This remarkable specimen now enriches the collec- 
tion of Mr. J. C. Daubuz of Killiow near Truro. Mr. Wittiam PErHericr, 
of Saint Austell, MSS. 
* “A slab of Jew’s-house-(grain)-tin...weighing 393 lbs. avoirdupois 
“«,..was found on the Barton of Carnanton, Parish of Mawgan i in Pydar, 
G6 two feet and a half under the surface, in swampy ground, and contiguous 
“‘to what is usually called a Jew’s House.” MrcHELL (Joun), Manual of 
Rea . 75. Poour, Journal of the Royal Institution of Cornwall, i, 
(No. iv.), p. 9. 
