primordial

First, earliest or original.

Characteristic of the earliest stage of the development of an organism, or relating to a primordium.

Primeval.

Of an element or isotope: occurring primordially (on Earth) (i.e. inherited from when the Earth was formed); because it is stable, or radioactive but so long-lived that some is left over from when the Earth was formed. For example, primordial radioisotopes (T = half-life in years) include uranium-235 (T = 7×10⁸), potassium-40 (T = 1.25×10⁹), uranium-238 (T = 4.5×10⁹), and thorium-232 (T = 1.4×10¹⁰).

A first principle or element.

A primordial condition or state.