Vein be found, it terminate
abruptly, or else end in some peculiar kind of Rock or Earth, which does,
as it were, close or Seal it up, without leaving any crack or cranny, or
otherwise? And whether the terminating part of the Vein tend upwards,
downwards, or neither? And whether in the places, where the Vein is
interrupted, there be any peculiar Stone or Earth, that does, as it were,
seal up the Extremity of it?

61. Whether it be observed; that the Ore in Tract of time may be brought to
afford any Silver or Gold, which it doth not afford, or more than it would
afford, if it were not so ripe? And whether it have been found, that the
Metalline part of the Vein grows so, that some part of the Mine will afford
Ore or Metal in tract of time, that did not so before? And whether to this
Maturation of the Mine, the being exposed to the free Air be necessary; or,
whether at least it conduce to the Acceleration of it; or otherwise?

62. Whether all the Ore, contained in the Mine, be of the self-same nature
and goodness; and, if not, what are the differing kinds; and how to be
discriminated and estimated?

63. What is the fineness and goodness of the Ore, by which the Mine is wont
to be estimated? And what are the marks and {339} characters, that
distinguish one sort from another?

64. What proportion of Metal it affords? (As in our _Iron-mines_ 'tis
observed, that about three Tuns of Iron-stone will afford one Tun of Metal:
And I have had _Lead-Ore_, which an Ingenious man, to whom I recommended
such Tryals, affirm'd to me to afford three parts in four of good Lead.)

65. Whether the Ore be pure in its kind from other Metals, and, if not, of
what Metals it participates; and in what proportion? Which is especially to
be Inquired into, in case the Mine be of a _base_ metal, that holds a
_noble_ metal: (As I have known it observ'd, that _Lead-Ore_, that is poor
in its own metal; affords more Silver, than other; and I remember, that the
_Ore_ lately mention'd, being rich in Lead, scarce afforded us upon the
_Cuppel_, an Atome of Silver. And _Matthesius_ informs us, that a little
Gold is not unfrequently found in _Iron-Ore_. And I have by me some Gold,
that never endur'd the Fire, taken out of a Lump of Tin-Ore.)

_About the sixth Title._

66. What are the mechanick and praevious Operations, as Beating, Grinding,
Washing, &c. that are used to separate the Ore from the Heterogeneous
Bodies, and prepare it for the Fire? Or whethe