Ann: Drilling Intersects Extensive Co-Ni Sulphide Mineralisation, page-65

They are all textural terms for the aggregates of sulphide or arsenide mineralisation which normally imply a crystallisation/re-crystallisation timing eg.
- massive - aggregates (clusters) of well formed crystals that form into void spaces implying first crystallisation.
- semi massive - aggregates (clusters) of large and small crystals form into restricted void space implying second crystallisation.
- blebby - aggregates (clusters) of rounded blobs or blebs forming between crystals along the interstitial spaces implying third crystallisation.
- disseminated - fine grained well formed crystals within host rock normally associated with primary crystallisation.
(All IMHO - DYOR) - GLTAH!