Dilute HCl (10%) is the standard reagent for identifying carbonate minerals — a drop on calcite produces immediate vigorous effervescence; dolomite requires powdering first. The test is simple; the acid is not trivially safe. This protocol applies to any ARE activity using acid for mineral testing.
Hydrochloric Acid (HCl) Field Testing Safety Protocol
Safe handling of dilute hydrochloric acid for carbonate identification in the field and shop.
Scope: Applies to field testing and shop demonstrations using dilute hydrochloric acid for carbonate identification.
Checklist
Use 10% (muriatic) acid only — never concentrated HCl.
Store acid in a sealed, labeled dropper bottle carried upright in a secondary container.
Wear nitrile gloves and safety glasses before opening the acid bottle.
Apply acid to the specimen — never bring the specimen to the bottle.
Have water and baking soda neutralizer within reach before beginning any acid test.
Do not conduct acid tests in wind that could blow reagent onto participants.
Wash hands thoroughly after testing even if gloves were used.
Keep acid locked away and out of reach during youth programs; acid testing is an adult-supervised activity only.