Mineral collecting: compare two labelled specimens

Mineral species have defined chemistry and crystal structure; rocks can contain several minerals. If you enjoy close comparisons, start with two labelled species. Borrowed pieces can become your first reference records, though arranging a loan may take longer than the session.

Keep each name with its source

Ask a knowledgeable collector, club or educational supplier for intact quartz and calcite teaching specimens, their original labels and any handling advice. Get the stated mineral name and collecting locality if known. Skip vague trade names as the only identification. Leave dusty, crumbling, fibrous, or hazard-labelled specimens for a qualified collection professional.

Place one specimen at a time on a clean table, supporting it from beneath rather than pinching projecting crystals. Keep food and drink away. Write M01 or M02 on its container and record, never on the specimen. Copy the label’s species name, who supplied or identified it, when you acquired it, and any stated collecting locality. Record where you obtained it separately from where it came from geologically. Write “unknown” for missing details and keep or photograph the old label. A supplied name is useful evidence, not independent verification.

Compare observations with references

In good light, note each piece’s colour, how its surface reflects light (lustre), whether light passes through, and any visible crystal shape. Photograph it beside its code and a ruler if useful. These are observations, even when the pieces look similarly pale or glassy. Colour alone cannot confirm a species.

In a separate reference column, use the Australian Museum’s properties guide and the Museum Wales quartz and calcite records. Quartz is silicon dioxide; calcite is calcium carbonate. Their published Mohs hardness values are 7 and 3, a relative scale of scratch resistance. Mark those values “reference, not tested.” A mismatch between your notes and a label is a question for a mineralogist, not a reason to rename the piece by sight.

Do not taste, scratch, crush, sand, acid-test or clean the specimens. Wash your hands afterward, and keep small pieces away from children and pets. Store each specimen and its original label in a separate compartment, protected from knocks and strong direct sunlight. After finishing both records, choose one feature to compare with a future, well-labelled specimen.