Abstract
We introduce a natural notion of determinants in matrix JB*-algebras, i.e. for hermitian matrices of biquaternions and for hermitian 3 x 3 matrices of complex octonions. We establish several properties of these determinants which are useful to understand the structure of the Cartan factor of type 6.
As a tool, we provide an explicit description of minimal projections in the Cartan factor of type 6 and a variety of its automorphisms.