3.2: Activity 3A- Assessing Hardness Values of Minerals
- Page ID
- 14516
Materials Needed
- Mineral kit, provided by your instructor. This will likely contain numbered samples.
- Hardness kit:
- Your fingernail
- A copper penny, plate or wire
- Glass plate or knife blade
- Steel nail
- Hand lens or magnifying glass (at minimum 10x). How do I use a hand lens? Hold it very close to your eye and bring the sample near the lens until it is in focus.
Recall, hardness is the scratching resistance of a mineral. You will need to determine if the mineral is harder or softer than the common material (Table 3.1). Use greater than (>) or less than (<) symbols to indicate the approximate hardness. For example, if your fingernail scratches your sample, look and feel for a gouge or groove in the sample, this sample would represent a hardness value of less than 2.5 (H<2.5).
Hardness number | Mineral | Test kit item |
---|---|---|
10 (hardest) | Diamond | |
9 | Corundum | |
8 | Topaz | 8.5 - Masonry drill bit |
7 | Quartz | |
6 | Feldspar | 6.5 - Steel nail |
5 | Apatite | 5.5 - Glass plate or knife blade |
4 | Fluorite | |
3 | Calcite | 3.5 – Copper (penny, plate, or wire) |
2 | Gypsum | 2.5 - fingernail |
1 (softest) | Talc |
Your instructor will indicate which three minerals to assess for this section. Use Table 3.1 for guidance.
- Sample number:
- Does your fingernail scratch this sample? YES NO
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Does your sample scratch the copper or penny? YES NO
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Does your sample scratch the glass? YES NO
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Sample number:
-
Does your fingernail scratch this sample? YES NO
-
Does your sample scratch the copper or penny? YES NO
-
Does your sample scratch the glass? YES NO
-
Sample number:
-
Does your fingernail scratch this sample? YES NO
-
Does your sample scratch the copper or penny? YES NO
-
Does your sample scratch the glass? YES NO
Attributions
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Table 3.1: “Mohs Hardness Scale” (CC-BY 4.0; Chloe Branciforte, own work)