Question: Radiohalos or pleochroic halos are microscopic, spherical shells of discolouration within minerals such as biotite that occur in granite and other igneous rocks, wider interest has been prompted by the claims of a creationist, by Robert V. Gentry, an American young Earth creationist and nuclear physicist, known for his claims that radiohalos provide evidence for a young age of what?
Sentence (from "Aphanite"): This geological texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments.
Relevant evidence: No