3.2: Activity 3A- Assessing Hardness Values of Minerals
- Page ID
- 14516
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)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
-
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
-
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)