Follow the clues, then name it.
Work through five supplied evidence cards. Compare more than color, explain your best match, and keep real unknown specimens labeled with a working ID.
- Grades 3–6 with support
- 30 minutes
- Indoors · no specimens needed
Before you investigate
A mineral has an ordered internal structure and a characteristic chemical composition. A rock can contain one mineral, several minerals, or other natural material. This lesson compares individual minerals.
- Read all the clues on a case card.
- Compare the card with the reference table.
- Choose a candidate and explain which clues support it.
- For a real specimen, ask what evidence would change your mind.
Your five-mineral reference
These clues help compare this lesson’s candidates. They do not identify every mineral you might find outside.
| Candidate | Hardness | Useful comparison |
|---|---|---|
| Quartz | 7 | Glassy; may have curved, shell-like fracture surfaces. |
| Calcite | 3 | Often glassy; three cleavage directions make slanted blocks. |
| Gypsum | 2 | Soft enough for a fingernail to scratch; some varieties look glassy or pearly. |
| Fluorite | 4 | Glassy; four cleavage directions; color varies widely. |
| Muscovite mica | About 2–2.5 | Light-colored mica with thin sheets and one excellent cleavage direction. |
Five mystery cases
0 of 5 cases matched
Case A
Glassy surface; measured hardness 7; curved fracture rather than repeating flat cleavage faces.
All five cases matched. Now explain two independent clues for one case to a partner. Matching a supplied case is practice, not confirmation of a field specimen.
Try a real observation tray
Use up to five adult-selected specimens or photographs. Give each a sample code, describe its surface, and record an untested property as “not tested.” Compare two independent clues before choosing a working ID.