Brearleyite (IMA 2010-062, Ca_(12)Al_(14)O_(32)Cl_2) is a Cl-bearing mayenite, occurring as fine-grained aggregates coexisting with hercynite, gehlenite, and perovskite in a rare krotite (CaAl_2O_4) dominant refractory inclusion from the Northwest Africa 1934 CV3 carbonaceous chondrite. The phase was characterized by SEM, TEM-SAED, micro-Raman, and EPMA. The mean chemical composition of the brearleyite is (wt%) Al_2O_3 48.48, CaO 45.73, Cl 5.12, FeO 0.80, Na_2O 0.12, TiO_2 0.03, –O 1.16, sum 99.12. The corresponding empirical formula calculated on the basis of 34 O+Cl atoms is (Ca_(11.91)Na_(0.06))Σ_(11.97)Al_(13.89)Fe_(0.16)Ti_(0.01))Σ_(14.06)O_(31.89)Cl_(2.11). The Raman spectrum of brealryeite indicates very close structural similarity to synthetic Ca_(12)Al_(14)O_(32)Cl_2. Rietveld refinement of an integrated TEM-SAED ring pattern from a FIB section quantifies this structural relationship and indicates that brearleyite is cubic, ⌈43d; a = 11.98(8) Å, V = 1719.1(2) Å3, and Z = 2. It has a framework structure in which AlO4 tetrahedra share corners to form eight-membered rings. Within this framework, the Cl atom is located at a special position (3/8,0,1/4) with 0.4(2) occupancy and Ca appears to be disordered on two partially occupied sites similar to synthetic Cl-mayenite. Brearleyite has a light olive color under diffuse reflected light and a calculated density of 2.797 g/cm3. Brearleyite is not only a new meteoritic Ca-,Al-phase, but also a new meteoritic Cl-rich phase. It likely formed by the reaction of krotite with Cl-bearing hot gases or fluids.