All notes semester 1 Flashcards
What is the softest mineral?
Talc
What is the hardest mineral?
Diamond
What is the scale of hardness?
Mohs scale of hardness
What mineral has a hardness of 2?
Gypsum
What mineral has a hardness of 3?
Calcite
What mineral has a hardness of 4?
Fluorite
What mineral has a hardness of 5?
Hematite
What mineral has a hardness of 6?
Orthoclase
What mineral has a hardness of 7?
Quartz
What mineral has a hardness of 8?
Topaz
What is quartz chemical formula?
SiO2
What mineral will react with a compass?
Magnetite
Galena
Colour - Lead grey* Lustre - Metallic Streak - Black* Hardness - 2.5 Density - High Cleavage -Cubic/3 lines of cleavage at 90 degrees* Comment - Looks like a pencil tip
Sphalerite
Colour - Dark grey* Lustre - Metallic Streak - Brown* Hardness - 4 Density - High Cleavage - Fractured/6 cleavage planes Comment - Sparkles
Pyrite
Colour - Gold* Lustre - Metallic Streak - Grey* Hardness - 6.5 Density - Medium Cleavage - 2 at 90 degrees* Comment - Gold squares in black sometimes.
Chalcopyrite
Colour - Yellow/Gold* Lustre - Metallic Streak - Black* Hardness - 4 Density - Medium Cleavage - 2 poor Comment - Black in many examples.
Marcasite
Colour - Orange/grey* Lustre -Earthy Streak - Orange* Hardness - 6.5 Density - Medium Cleavage - One Comment - Tubes or half spheres*
Arsenopyrite
Colour - Grey* Lustre - Metallic Streak - Black* Hardness - 6 Density - High Cleavage - One Comment -White glassy bits in a metallic grey - smells like garlic when broken.*
Stibnite
Colour - Silver* Lustre - Metallic Streak - Black Hardness - 2 Density - Low Cleavage - Grooves/striations* Comment - Elongated crystals*
Quartz
Colour - White Lustre - Glassy* Streak - None Hardness - 7* Density - Medium Cleavage - Concoidal fracture* Comment - Clear* and often grey or white
Amethyst
Colour - Purple* Lustre - Vitreous* Streak - None Hardness - 7* Density - Low Cleavage - Sometime concoidal Comment - Purple version of quartz
Hematite
Colour - Dark grey* Lustre - Metallic Streak - Red* Hardness - 5 Density - High Cleavage - None Comment - Can be grey or red*
Magnetite
Colour - Dark grey Lustre - Metallic* Streak - Grey Hardness - 6 Density - High* Cleavage - None Comment - Magnetic and will make compass move*
Chromite
Colour - Grey* Lustre - Metallic/sparkly* Streak - None* Hardness - 5.5 Density - Medium Cleavage - None Comment - Plain looking with no crystals.*
Cassiterite
Colour - Yellow/White/Grey Lustre - Metallic/glossy* Streak - None Hardness - 6.5 Density - Low Cleavage - Poor Comment - Obvious crystals in some specimens*
Halite
Colour - Clear* Lustre - Vitreous* Streak - None Hardness - 2.5 Density - Low Cleavage - Cubic* Comment - Salty*
Fluorite
Colour - Brown/green* Lustre - Vitreous* Streak - None Hardness - 4 Density - Medium Cleavage - 4 cubes common* Comment - Like a dirty quartz*
Calcite
Colour - Orange/Cream/Clear* Lustre - Vitreous (sometimes hard to see)* Streak - None Hardness - 3 Density - Low* Cleavage - 3 Comment - None
Malachite
Colour - Green/Bluey* Lustre - Earthy* Streak - Green* Hardness - 4 Density - Medium Cleavage - 2 Comment - None
Barite
Colour - Colourless/brown/cream* Lustre - Vitreous (not always) Streak - None* Hardness - 3 Density - Medium* Cleavage - 2 at 90 degrees Comment - None
Gypsum
Colour - Clear/creamy* Lustre - Pearly and Vitreous/Metallic Streak - None Hardness - 2.5* Density - Low* Cleavage - 3 or fiberous/striations* Comment - Less dense than Barite
Tourmaline
Colour - Black* Lustre - Pearly* Streak - None Hardness - 7.5* Density - Medium Cleavage - Striated*/Fibrous/none Comment - None
Olivine
Colour - Green* Lustre - Metallic/Glittery* Streak - None* Hardness - 6.5* Density - Medium Cleavage - None Comment -None
Hornblende
Colour - Black* Lustre - Pearly* Streak - None Hardness - 6 Density - Low Cleavage - 2 (squared edges)* Comment - None
Muscovite
Colour - Clear* Lustre - Vitreous Streak - None Hardness - 2 or less* Density - Low Cleavage - 1 (Sheets)* Comment - Flakey*
Orthoclase
Colour - Cream/yellow* Lustre - Pearly Streak - Differs Hardness - 6* Density - Low Cleavage - 2 at 90 degrees* Comment - None
Define Vitreous.
Glass like in appearance or properties.
What does PPL mean?
Plain polarised light.
What does XPL mean?
Cross polarised light.
What is a microscope eyepiece called?
Ocular.
How would you draw a microscopes field of view?
A circle with two halves for PPL on the left and XPL on the right. Annotate it describing colours, twinning, relief and names of minerals.
What kind of microscope do we use to look at thin-sections?
Petrological microscope.
What does olivine look like in thin section?
Pink/Blue very bright colours. Edges not smooth. High relief.
What are completely black spots in thin section?
Opaques. Can’t be identified.
What does Pyroxene look like in thin section?
Orange.
What should be identified in thin section?
Crystal size, mineralogy, mode, texture and draw a diagram. Finally name and classification.
Describe porphyritic granite.
-Porphyritic rock.
-Large crystals embedded in a finer groundmass
-Phenocrysts of alkali feldspar (pink)
-Contains plagioclase feldspar, quartz, amphibole and
sometimes biotie or muscovite mica.
-Inequigranular texture
-Subhedral crystals
What are euhedral crystals?
Well formed, sharp crystal faces.
What are anhedral crystals?
No well formed crystal faces.
Describe olivine gabbro.
-Contains Plagioclase feldspar, olivine, pyroxene and
small amounts of amphibole and biotite mica.
-Inequigranular texture
-Subhedral crystals
Describe hornblende quartz diorite.
- Contains Hornblende, plagioclase feldspar, quartz and alkali feldspar.
- Inequigranular texture
- Euhedral crystals
- Some elongated crystals
Describe fine grained dolerite.
- Contains plagioclase feldspar, pyroxene, hornblend, alkali feldspar and quartz.
- Equigranular texture
- Rapid cooling
What does lustre mean?
The way light is reflected from mineral surfaces.
What is the systematic way of recording mineral specimens?
Colour, streak, lustre, density, cleavage, fracture, hardness and others e.g taste.
How would you identify Alkali Feldspar?
Also known a K/potassium feldspar. Pink*/grey/white. Isolated grains. Two cleavage planes at 90 = sharp edges. Pearly.
How would you identify Plagioclase Feldspar?
White/grey/green.
Isolated grains.
Two cleavage planes at 90 = sharp edges.
Striations.
How would you identify Quartz? In hand specimen.
Usually colourless, some coloured hues, grey.
Can be very fine or large crystals.
Glassy.
How would you identify Amphibole/Hornblende?
Long crystals.
Fibrous.
How would you identify Biotite Mica?
Black/dark brown.
Soft - easy to scratch.
Shiny.
How would you identify Muscovite Mica?
Colourless, grey/green tint.
Soft - easy to scratch.
Disk shaped crystals from some angles.
How would you identify Olivine? In hand specimen.
Olive/grey/brown/green.
Glassy.
How would you identify Pyroxene?
Granular.
Hard.
Dark coloured.
How do you fully describe an igneous rock?
Colour (general and of individual crystals), crystal size, mineralogy, mode (% of each mineral) and texture (relationship between crystals).
What are the different crystal sizes in a rock?
Fine-grained (<1mm), Medium-grained (1-5mm) and cours-grained (>5mm)