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Layered semiconductors have recently emerged as capable host materials for novel quantum applications ranging from phonics to sensing. Most studies have focused on artificial layered materials, while natural layered materials, such as talc and other silicates, have remained largely unexplored despite their desirable properties, e.g, wide direct bandgap, low concentration of optically active defects, and low abundance of nuclear spins. In this article, we carry out a comprehensive computational study of pristine and defective talc layers and discuss their potential applications. After investigating bulk properties, such as lattice parameters, band structure, and dielectric constant, we study the electronic structure, charge states, spin and optical properties of vacancy defects, metal, metalloid, and non-metallic impurities. Our results establish the basis for identifying color centers, electron paramagnetic resonance centers, potential spin quantum bits, and p and n-type dopants. These findings mature the theory of talc and point toward potential applications in quantum technologies.