In this paper we study finite clusters in a high density Boolean model with
balls of two distinct sizes. Alexander (1993) studied the geometric struct
ures of finite clusters in a high density Boolean model with balls of fixed
size and showed that the only possible structure admitted by such events i
s that all Poisson points comprising the cluster are packed tightly inside
a small sphere. When the balls are of varying sizes, the event that the clu
ster consists of k(1) big balls and k(2) small balls (both k(1), k(2) great
er than or equal to 1) occurs only when the centres of all big balls are co
mpressed in a small sphere and the centres of the small balls are distribut
ed uniformly inside the region formed by the big balls in such a way that t
he small balls are totally contained inside the big balls. We also show tha
t it is most likely that a finite cluster in a high density Boolean model w
ith varying ball sizes is made up only of small balls.