The phrase "a core stone" is correct and usable in written English.
It can be used in contexts where you are referring to a fundamental or essential element of something, such as a concept, idea, or structure.
Example: "Trust is a core stone of any successful relationship, providing the foundation for open communication and mutual respect."
Alternatives: "a fundamental element" or "a key component."
Methodological solutions of Prof. G.A. Ilizarov are the core stone of the contemporary bone lengthening and reconstruction surgery.
Security-critical communication is core stone in decentralized, highly dynamic and unpredictable mobile pervasive environment where small, effective and resource-restricted devices are communicating seamlessly.
Nowadays, his methodological solutions are the core stone of limb lengthening and reconstruction surgery and have been acknowledged in the orthopaedic world as one of the greatest contributions to treating bone pathologies [5, 6, 7].
Layers of turf could also be added to stabilise the motte as it was built up, or a core of stones placed as the heart of the structure to provide strength.
In regions where alternating humid and arid climates or human activity have led to erosional stripping of weathered zones, mammoth boulder piles of exhumed core stones exist.
Boulders of foliated granite in the hot springs area do not appear altered, perhaps because they are resistant core stones within the clay-altered granite.
Its walls are 1.8 m thick at the base, with a core of flint stone, faced on the inside and outside with brick; the archaeologist T. P. Smith considers it to feature some "of the finest medieval brickwork" in England.
Its walls, 1.8 m thick at the base, are made of a core of flint stone, faced on the inside and outside with brick, and various putlog holes can still be seen in the walls.
The method of above-ground wall construction appears to have been the same for all groups: a core of mud and stone covered with plaster or well-cut trachyte.
This is the "prepared-core" tool, whereby a stone core was elaborately shaped until a single blow, perhaps with a hammer made of a "soft" material such as bone, would detach a virtually finished tool with a continuous cutting surface around its periphery.
