According to The Mining Valuation Handbook (2nd Edition) by Dr....

According to The Mining Valuation Handbook (2nd Edition) by Dr. Victor Rudenno; "disseminated" means:

"descriptive, of mineral grains which are scattered throughout the host rock."

Dr Rudenno doesn't define "massive", but the impression I get from a mate who's a metallurgist is there are larger clumps of mineralised rock in the host rock.

Western Areas (WSA) usually report their nickel exploration in terms of "massive" and "disseminated", with the "massive" seemingly always of a much higher grade.

Happy to be corrected on any of this by someone in the know.....