The catalog number
Every specimen gets a number. The number lives in three places: a small inked dot on a non-display surface of the specimen itself, a printed paper label inside the storage box, and the master catalog (a spreadsheet, FileMaker database, or dedicated collector software). The number is the link — without it, specimens and labels separate over time and information is lost permanently.
Required fields per specimen
Mineral name (preferably IMA-approved). Locality at the highest specificity available — mine name, level, pocket if known, then town, province/state, country. Dimensions in mm. Acquisition date. Source (dealer name and city). Acquisition price. Catalog number. Notes: any treatments, repairs, prior collection history. Photo if possible. The minimum data fits on a 3×5 card; missing data is irreversible later.
Surviving you
Digital catalog backed up to at least two locations including offsite cloud. Master list printed annually and stored separately from the collection. Notes on collection plan in case of unexpected absence: which museum is willing to accept this collection? Which dealer is fair? Which family member knows what 'cabinet specimens' means? Specimens without instructions get tossed by people who don't know what they're looking at.