How to say "in solid rock" in Latin to convey specific technical meaning?

Question

I am writing a paper that describes nuclear reactions that take place in the earth's crust leading to the formation of volatile gases. In several places, I need to distinguish between things that happen in solid rock vs in microscopic gas pockets that can form in pores and between grain boundaries. I would like to introduce a technical term to denote the former since I find myself repeating the verbose distinction several times.

How best to render "in rock" in Latin? My dictionary suggests "in saxo" and "in scopulo", but those both seem to suggest a rocky outcropping or a piece of rock, and I'm hoping to convey something more like "in solid bedrock". "In silico" would probably work, except that it already has a very different technical meaning in this field (referring to simulations "on silicon" as opposed to experiment).

Answer 1

petra is the word sometimes used for the material of rock, also lapis

In Pliny at one point it reads:

Sunt in Bononiensi Italiae parte breves maculae complexu silicis alligatae

(In the region of Bologna in Italy small streaks occur tightly embedded within hard rock...)

The inner part of the earth is called the viscera and in mining the mother rock is referred to as the viscera montium.

In De Re Metallica and other books on mining, the authors frequently speak of commissurae saxorum (seams of the rocks).