Everything that has to be on the label
Updated
Nothing here is required by law. All of it is required by the next person to own the specimen.
The six required fields
1 · Species. The accepted species name. Associated species after it, in order of prominence. Variety name alongside the species, not instead of it.
2 · Locality. Most specific to least: working, district, county or region, state or province, country. Only to the level you actually know.
3 · Collector or source. Who found it, or who you got it from.
4 · Date. Collected, or acquired.
5 · Catalog number. Yours, matching the number on the specimen and the row in the catalog.
6 · Size or weight.
The four worth adding
Prior collection, where there is provenance. It is value and it should travel.
Identification basis. Visual, streak and hardness, XRD, per the dealer.
Treatments and repairs. Anything done after it left the ground.
Hazard note, for asbestiform, radioactive, arsenic-bearing or lead-bearing material. The person who inherits this collection will not know unless you write it down.
The qualifiers
These are not weaknesses. They are what make the rest of the label trustworthy.
"as received": the locality is the seller's, unverified.
"said to be from": reported, not established.
"no locality data": a complete and honest entry.
What does not belong: a price, and a guess written as a fact.
Materials
Acid-free, lignin-free stock, because a decaying sulfide produces sulfuric acid and a wooden cabinet produces acetic acid, and both attack paper.
Pigment ink, laser toner or pencil. Not dye-based inkjet, which runs.
Loose in the box, readable without moving the specimen, and never adhered to the stone.