The hydraulic fracturing in hydrothermal systems is

indicated by (i) simultaneous opening of the entire network

of fractures oriented in various directions, (ii)

arising of new tension cracks and filling of all fissures

with a common mineral assemblage, (iii) a complex

relationship (conjugation) of simultaneously formed

and closely spaced fracture systems, (iv) uneven contacts

of veins; (v) angular fragments in breccia without

signs of their grinding [18]; (vi) lithological identity of

fragments and country rocks, and (vii) the occurrence

of rock fragments incompletely detached from country

rocks in vein selvages.

The above list of indications may be supplemented

by the following signs: (i) upward branching of veins

and an increase in number and size of orebodies in this

direction [7, 8, 15] and (ii) the progressive (in space and

time) variation of the ore texture from disseminated via

stringer–disseminated and reticulate to brecciated and

cockade in the intermediate zone and massive and

drusy in the following zones.

This was taken from the research paper by Mike and I am just now reading it and like this part of it, specifically when they mention: arising of new tension cracks and filling of all fissures

with a common mineral assemblage

This is why JT believes that the grade will be similar at all levels.

Glorieux