  This paper presents an ontology of portions of matter with practical
implications across scientific and industrial domains. The ontology is
developed under the Unified Foundational Ontology (UFO), which uses the concept
of quantity to represent topologically maximally self-connected portions of
matter. The proposed ontology introduces the granuleOf parthood relation,
holding between objects and portions of matter. It also discusses the
constitution of quantities by collections of granules, the representation of
sub-portions of matter, and the tracking of matter provenance between
quantities using historical relations. Lastly, a case study is presented to
demonstrate the use of the portion of matter ontology in the geology domain for
an Oil & Gas industry application. In the case study, we model how to represent
the historical relation between an original portion of rock and the
sub-portions created during the industrial process. Lastly, future research
directions are outlined, including investigating granularity levels and
defining a taxonomy of events.
