[ 26o ] 
ings of the cryftal Drops, without any Continuity, 
or mutual Conta&j and in this Calc, when the 
pearly Drops are tnemfelves bright and tranfparent, 
and the Stone they fix on, of an Agate Colour, or 
any lively Oppofition, the Incruftation is exceedingly 
beautiful. On one Ihotten blifter’d Spar, I find the 
Incruftation white, not pellucid, flowing in parallel 
Threads by each other (Fig. 2. Tab. V.), in feveral 
Places palling from one Tubercle to another, with- 
out touching the interfpers’d Hollows 5 by which I 
conclude, that this Spar was fixed on the perpendi- 
cular Side of a Fiflure ; that the Juice of this In- 
cruftation was of the St a la Bites Kind, and, proceed- 
ing from the fame Caufe, defeended in a fimilar Di- 
rection. 
Fig. 3. Tab. V. Is a Bunch of femi-pellucid Spar, 
fhot into reclined Cones, making an Angle of 30 
Degrees, with the Surface of the Stone ; the Sides 
of thefe Cones are a very curious Fretwork of 
little Spires or Briftles, many of them fharp as the - 
fmallcft Needle, and pointing nearly in the fame Di- 
rection, as the Cone on which they rife. The Sur- 
face of thefe Shoots is of a ferrugineous Tint, but 
their inner Subftance pellucid, very little fhort of 
that Spar, which for its Clearnefs is called Cryftal, 
and 
(14) Incruftations are fo many evident Proofs of Scones not being 
formed all at the fame Time } for many Corni/b Diamonds^ and columnar 
Shoots of Tin, Cubes of Mundic, and Grains of Lead are often 
broke off from thefe their Inclofures ; but the angular Cavities, with 
their ftrait Edges and fmooth Sides, ftill appear in the Incruftation ; 
which plainly fhews, that the Diamonds and Tin Shoots, &c. were firft 
form’d and harden’d, and then furrounded and united into one Lump, 
by a fucceffive Induration of thefe Cryftal or Spar Crufts. 
