14.1: Mineral Identification Tables
- Page ID
- 49832
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)| Streak | Hardness | Cleavage | Summary | Mineral Name |
|---|---|---|---|---|
| Black, gray, green | >5.5 | indistinct |
Color: Golden yellow, Luster: bright metallic, streak: greenish or brownish black/gray, D=4.9, H=6.25 Commonly forms cubic crystals, some may have striated faces. Commonly referred to as “Fool’s Gold”. |
Pyrite |
| indistinct |
Color: Black to dark gray, Luster: pearly, Streak: black, D=5.2, H=5.5–6 May be attracted to a magnet or magnetized |
Magnetite | ||
| <5.5 | excellent; three directions at 90° |
Color: Silver or lead gray, Luster: bright metallic, Streak: gray, D=7, H=2.5 Three cleavage directions form cubes, high density |
Galena | |
| indistinct; poor in one direction | Color: Brassy yellow, may tarnish to dull brass or brown, Luster: metallic to submetallic, Streak: greenish-brown, D=4.2, H=3.5–4 | Chalcopyrite | ||
| indistinct; poor in one direction | Looks like a brassy or tarnished version of pyrite | Graphite | ||
| Red | 5–6 | indistinct |
Color: steel gray, Luster: bright metallic, Streak: red, D=5.3, H=5–6 Commonly appears micaceous or foliated, some specimens may be slightly magnetic |
Hematite (specular) |
| Yellow-brown | <5.5 | six directions, difficult to distinguish |
Color: Dark brown to yellowish-brown, Luster: metallic to submetallic or resinous, Streak: brown or yellow, D=4, H=3.5–4 May smell slightly like sulfur when powdered on streak plate |
Sphalerite |
| Streak | Hardness | Cleavage | Summary | Mineral Name |
|---|---|---|---|---|
| Dark colored | >5.5 | good to excellent; two directions at 56° and 124° |
Color: Black, Luster: Vitreous, Streak: White to gray or greenish gray, D=3.0-3.5, H=5.5 Cleavage more obvious when rotated in bright light |
Hornblende |
| good to excellent; two directions at ~90° |
Color: medium green to greenish black, some sample light greenish gray, Luster: Vitreous, Streak: white to green, D=3.4, H=6 Commonly forms large blocky crystals, cleavage not always obvious |
Diopside (pyroxene) | ||
| good to excellent; two directions at ~90° |
Color: greenish gray to black, Luster: Vitreous, Streak: White, D=2.7, H=6-6.5 Individuals crystals have striations on cleavage planes, some samples are iridescent, commonly occurs in coarsely crystalline aggregates |
Plagioclase Feldspar (Labradorite or Anorthite) | ||
| none |
Color: Black, Luster: Vitreous, Streak: White, D=3-3.2, H=7-7.5 Looks superficially like hornblende, good samples form elongate striated prisms with triangular cross-sections |
Tourmaline | ||
| none/indistinct |
Color: most commonly red to brown, Luster: Vitreous; Streak: white; D = 3.1-4.3; H = 6.5-7.5 Color: most commonly red to brown, Luster: Vitreous; Streak: white; D = 3.1-4.3; H = 6.5-7.5 |
Garnet | ||
| none |
Color: red to gray, Luster: Earthy, Streak: Red, D=5.2, H=5-6 Red, rusty color with a drab luster. |
Hematite | ||
| indistinct |
Color: Black to dark gray, Luster: pearly or submetallic, Streak: black, D=5.2, H=5.5-6 Color: Black to dark gray, Luster: pearly or submetallic, Streak: black, D=5.2, H=5.5-6 |
Magnetite | ||
| indistinct |
Color: olive green to army green, Luster: Vitreous, Streak: white to light green, D=3.2-4.4, H=6.5-7 Distinct green color, commonly forms granular crystalline masses |
Olivine | ||
| <5.5 | good to excellent; one direction |
Color: Black, Luster: Vitreous to pearly (looks like plastic), Streak: White to gray, D=2.7-3.4, H=2.5-3 Perfect cleavage causes the specimen to break in to thin sheets |
Biotite Mica | |
| six directions, difficult to distinguish |
Color: Dark brown to yellowish-brown, Luster: metallic to submetallic or resinous, Streak: Brown or yellow, D=4, H-3.5-4 May smell slightly like sulfur when powdered on streak plate |
Sphalerite | ||
| poor to absent; some may show three directions ≠90° |
Color: Reddish brown, Luster: Vitreous to pearly, Streak: White, D=3.9, H=3.5-4.5 May react with HCl when powdered, often found as nodules in sedimentary rocks, may appear broadly similar to garnet or hematite. |
Siderite |
| Streak | Hardness | Cleavage | Summary | Mineral Name |
|---|---|---|---|---|
| Light colored | >5.5 | good to excellent; two directions at ~90° |
Color: Pink to white to light gray, Luster: Vitreous to resinous, Streak: White, D=2.7, H=6-6.5 Cleavage planes show white exsolution lamellae that give it a fibrous look similar to muscle tissue |
Potassium Feldspar |
| good to excellent; two directions at ~90° |
Color: light greenish gray to dark gray, Luster: Vitreous, Streak: White, D=2.7, H=6-6.5 Striations on cleavage planes in good samples |
Plagioclase Feldspar (Albite) | ||
| good to excellent; two directions at ~90° |
Color: medium green to greenish black, Luster: Vitreous, Streak: white to green, D=3.4, H=6 Commonly forms large blocky crystals, cleavage not always obvious, looks like a green feldspar |
Diopside (pyroxene) | ||
| none; crystals common |
Color: clear, white, purple, pink, gray, Luster: Vitreous, Streak: white, D=2.6, H=7. Conchoidal fracture, commonly forms large 6-sided crystals |
Quartz | ||
| indistinct |
Color: olive green to army green, Luster: Vitreous, Streak: white to light green, D=3.2-4.4, H=6.5-7 Distinct green color, commonly forms granular crystalline masses |
Olivine | ||
| good; four directions |
Colors: Commonly green or purple, Luster: Vitreous, streak: white, D=3.2, H=4 Looks similar to quartz but does not scratch glass. |
Flourite | ||
| excellent; three directions ≠90° |
Color: White to clear, variety of other colors possible, Luster: vitreous to earthy, streak: white to gray, D=3, H=3 Effervesces vigorously in dilute HCl, commonly breaks into rhombohedrons, clear specimens may show double refraction |
Calcite | ||
| <5.5 | excellent; three directions ≠90° |
Color: Commonly white to clear, other colors possible, Luster: vitreous to pearly, streak: white to gray, D=2.9, H=3.5-4 Effervesces when powdered, commonly breaks into rhombohedrons, looks very similar to calcite |
Dolomite | |
| excellent; three directions at 90° |
Effervesces when powdered, commonly breaks into rhombohedrons, looks very similar to calcite Tastes like salt, three cleavage directions at 90° causes it to break in to small cubes |
Halite | ||
| indistinct; one direction |
Color: Pale green to white or light gray, Luster: greasy to pearly, Streak: white, D=2.7, H=1. Has a greasy or soapy feel |
Talc | ||
| excellent; one direction |
Color: white to light yellow or brown, Luster: vitreous to pearly (looks like plastic), Streak: white, D=2.8, H=2.5-3.5 Perfect cleavage causes the specimen to break in to thin sheets |
Muscovite Mica | ||
| good; one direction |
Color: clear to white, Luster: vitreous, Streak: white, D=2.3, H=2 |
Gypsum (Selenite) | ||
| excellent; three directions ≠90° |
Color: White to clear, variety of other colors possible, Luster: vitreous to earthy, streak: white to gray, D=3, H=3 Effervesces vigorously in dilute HCl, commonly breaks into rhombohedrons, clear specimens may show double refraction |
Calcite | ||
| indistinct | Color: White or other subtle light shades of off-white, Luster: earthy to pearly, Streak: white, D=2.3, H=2 | Gypsum (Alabaster) | ||
| indistinct; one direction |
Color: Pale green to white or light gray, Luster: greasy to pearly, Streak: white, D=2.7, H=1. Has a greasy or soapy feel |
Talc | ||
| indistinct; two directions |
Color: bright yellow, Luster: Earthy to resinous, Streak: yellow to yellow-white, D=2, H=2 Distinctive yellow color, may form crystals |
Sulfur | ||
| good; four directions |
Colors: Commonly green, purple, or light blue, Luster: Vitreous, streak: white, D=3.2, H=4 Looks similar to quartz but does not scratch glass. |
Flourite |