Presentation is loading. Please wait.

Presentation is loading. Please wait.

ROCKS under the microscope. The ROCKS you need to know granite diorite gabbro dolerite basalt shelly limestone sandstone arkose greywacke marble schist.

Similar presentations


Presentation on theme: "ROCKS under the microscope. The ROCKS you need to know granite diorite gabbro dolerite basalt shelly limestone sandstone arkose greywacke marble schist."— Presentation transcript:

1 ROCKS under the microscope

2 The ROCKS you need to know granite diorite gabbro dolerite basalt shelly limestone sandstone arkose greywacke marble schist

3 PPL XPL Granite Note how light and clear it is under PPL and grey/white/black under XPL; main minerals – feldspars (often microcline), quartz, biotite and muscovite quartz muscovite biotite plagioclase

4 amphibole plagioclase biotite PPL XPL Diorite Darker under PPL than granite with more coloured minerals; much plagioclase and amphibole/biotite, only small amount of quartz

5 PPLXPL Gabbro Coarse-grained; darker under PPL and brightly coloured under XPL; main minerals – plagioclase, pyroxene and olivine olivine pyroxene plagioclase

6 PPLXPL Dolerite M edium-grained; darker under PPL and brightly coloured under XPL; main minerals – plagioclase (often in form of laths), pyroxene (intergrown through other crystals) and olivine plagioclase pyroxene

7 PPLXPL Basalt F ine-grained; darker under PPL and brightly coloured under XPL; main minerals – plagioclase, pyroxene and olivine; often porphyritic (large well-formed crystals in fine groundmass) pyroxene fine groundmass of plagioclase & iron minerals

8 calcite PPLXPL Shelly limestone Dark under PPL and dark pearly shades under XPL; main mineral – calcite; note the fossils.

9 quartz PPLXPL Sandstone Rounded quartz fragments; light under PPL and grey/white/black under XPL; main mineral – quartz

10 microcline quartz microcline PPLXPL Arkose More angular quartz and feldspar fragments; light under PPL and grey/white/black under XPL; main minerals – quartz and microcline

11 quartz muddy matrix muddy matrix rock fragment rock fragment PPL XPL Greywacke F ragments variable in shape, size and type; light under PPL and grey/white/black under XPL; main mineral – quartz but with rock fragments, feldspar and minor micas; look out for the muddy matrix!

12 calcite PPLXPL Marble Crystalline with perfect cleavages evident; light under PPL and pearly shades under XPL; main mineral – calcite.

13 garnet muscovite quartz PPLXPL Schist Minerals showing foliation; light under PPL and brightly coloured under XPL; main minerals – muscovite, biotite, garnet, quartz and feldspar garnet muscovite quartz


Download ppt "ROCKS under the microscope. The ROCKS you need to know granite diorite gabbro dolerite basalt shelly limestone sandstone arkose greywacke marble schist."

Similar presentations


Ads by Google