अभ्रक (अंग्रेजी:Mica) एक बहुपयोगी खनिज है जो आग्नेय एवं कायांतरित चट्टानों में खण्डों के रूप में पाया जाता है। इसे बहुत पतली-पतली परतों में चीरा जा सकता है। यह रंगरहित या हलके पीले, हरे या काले रंग का होता है।

Micas are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists, and "books" of mica several feet across have been found in some pegmatites.