  The three dimensional structure of large packings of monosized spheres with
volume fractions ranging between 0.58 and 0.64 has been studied with X-ray
Computed Tomography. We search for signatures of organization, we classify
local arrangements and we explore the effects of local geometrical constrains
on the global packing. This study is the largest and the most accurate
empirical analysis of disordered packings at the grain-scale to date with over
140,000 sphere coordinates mapped. We discuss topological and geometrical ways
to characterize and classify these systems, and discuss implications that local
geometry can have on the mechanisms of formation of these amorphous structures.
