Trabajo ganador en el área de Geología en el Foro TIS, PERUMIN 35.Por: Raymond Rivera Cornejo, geólogo principal en First Quantum Minerals y Federico Cernuschi, consultor externo.AbstractThis paper aims to update the knowledge of a not so well known type of veinlets called Early Halos (EH). Recognizing these veinlets can be very useful for the lateral and vertical vectoring of a porphyritic system, but due to the scarce information available about them they are often underestimated, unnoticed or even confused with other types.Early Halos are more common in Cu - Mo porphyries, while in porphyries with affinity towards Au (Cu - Au / Au - Cu) they are usually scarcer or absent, but even so their weak presence can serve as a vectoring tool.Meyer, 1965 had already reported this type of veinlets in Butte (Montana), but in many other deposits Early Halos were not recognized as such until the compilation work of Proffett (2009). However, they were described early at Los Pelambres by Atkinson et al., 1996. More recently they have been reported in various deposits such as Haquira East (Cernuschi et al., 2013) and Copper Cliff (Montana, Uribe-Mogollon & Maher, 2018). This paper presents a compilation of a series of field observations made on several porphyritic systems (economic and non-economic) and tries to summarize the main characteristics, obtaining a classification that includes all types of Early Halos reported in other studies and proposes how their occurrence would be and what would be their geological-economic implication within a porphyritic system. Finally, it summarizes three main types of Early Halos, which are known as: Early Dark Micaceous (EDM), Pale Green Sericite (PGS) and Green Sericite (GRS).