  Phyllosilicate minerals, which form a class of naturally occurring layered
materials (LMs), have been recently considered as a low-cost source of
two-dimensional (2D) materials. Clinochlore [Mg5Al(AlSi3)O10(OH)8] is one of
the most abundant phyllosilicate minerals in nature, exhibiting the capability
to be mechanically exfoliated down to a few layers. An important characteristic
clinochlore is the natural occurrence of defects and impurities which can
strongly affect their optoelectronic properties, possibly in technologically
interesting ways. In the present work, we carry out a thorough investigation of
the clinochlore structure on both bulk and 2D exfoliated forms, discussing its
optical features and the influence of the insertion of impurities on its
macroscopic properties. Several experimental techniques are employed, followed
by theoretical first-principles calculations considering several types of
naturally-ocurring transition metal impurities in the mineral lattice and their
effect on electronic and optical properties. We demonstrate the existence of
requirements concerning surface quality and insulating properties of
clinochlore that are mandatory for its suitable application in nanoelectronic
devices. The results presented in this work provide important informations for
clinochlore potential applications and establish a basis for further works that
intend to optimize its properties to relevant 2D technological applications
through defect engineering.
