1. When I was young!!!

2. Metamorphic rocks are formed from other rocks Which are changed by heat and pressure

3. Metamorphic Rocks • generated by recrystallization of either igneous or sedimentary rocks by the action of any or all of the following: • Pressure • Temperature • Mineral Rich Fluids • The type of metamorphic rock is determined by the parent rock, and the P/T conditions. Metamorphism causes: Growth of new minerals Deformation and rotation of mineral grains Recrystallization of minerals as larger grains

4. Metamorphic Minerals • Chlorite • Talc • Graphite • Asbestos • Kyanite • Staurolite • Siliminite • Corundum

5. Contact Metamorphic Rocks generated mainly by temperature at the margins of igneous intrusions..

6. Index Minerals • Minerals associated with the grade of metamorphism.

8. Limestone into Marble • Texture - granular. • Grain size - medium grained; can see interlocking calcite • crystals with the naked eye.Hardness - hard, although component mineral is soft (calcite is 3 on Moh's scale of hardness). • Colour - variable - pure marble is white but marble exists in a wide variety of colours all the way through to black • Mineralogy - calcite. • Other features - generally gritty to touch.

9. Sandstone to Limestone Texture - granular. Grain size - medium grained; can see interlocking quartz crystals with the naked eye. Hardness - hard. Colour - variable - pure quartzite is white but quartzite exists in a wide variety of colours. Mineralogy - quartz. Other features - generally gritty to touch. • Quartzite

10. Mudstone - hornfels • Texture - granular. • Grain size - medium grained; can see interlocking crystals with the naked eye. • Hardness - hard. • Colour – greys - blacks • Mineralogy – no specific composition. • Other features - generally gritty to touch.

11. Regional Metamorphism

12. Foliation • Foliation is formed by the orientation in the rocks. • Foliation is seen as banding in the rocks.

13. Metamorphic Grades

14. Slaty • Texture - foliated, foliation on a mm scale. • Grain size - very fine-grained; crystals not visible to the naked eye. • Hardness - hard and brittle.Colour - variable - black, shades of blue, green, red, brown and buff. • Mineralogy - contains mica minerals (biotote, chlorite, muscovite) which typically impart a sheen on foliation surfaces; can contain cubic pyrite porphyroblasts.

15. Schistose texture • Texture - foliated, foliation on mm to cm scale.Grain size - fine to medium grained; can often see crystals with the naked eye.Hardness - generally hard.Colour - variable - often alternating lighter and darker bands, often shiny.Mineralogy - mica minerals (biotite, chlorite, muscovite), quartz and plagioclase often present as monomineralic bands, garnetporphyroblasts common.

16. Gneiss texture • Texture - foliated, foliation on a scale of cm or more. • Grain size -medium to coarse grained; can see crystals with the naked eye. • Hardness - hard. • Colour - variable - generally alternating lighter and darker sub-parallel discontinuous bands. • Mineralogy - felsic minerals such as feldspar (orthoclase, plagioclase) and quartz generally form the light coloured bands; mafic minerals such as biotite, pyroxene (augite) and amphibole (hornblende) generally form the dark coloured bands; garnet porphyroblasts common. • Large banding. • Distinct dark and light bending.

17. Amphibolite • Made mainly of Amphibole. • Other minerals hornblende, Plagioclase and Garnet • Formed when Basalt undergoes high pressure and temperature. • Foliations present

18. Greenschist • Low grade • Chlorite, epidote, actinolite. • Green in colour. • Changes from the original mafic minerals as water reacts with the minerals

19. Dynamic Metamorphism

20. Mylonite • Fine grained rock • Thin laminations • Large porphyrblasts of garnet and k feldspar during metamorphism. • Recrystalised quartz and Mica • Banding is called a ribbon texture

21. Fault Breccia • Cataclastic rock • Formed by fault movement • Cemented by minerals.

22. a-sedimentary rocks b-contact metamorphic c-burial metamorphic d-regional metamorphic e-igneous rock

23. What does metamorphis do? • High Temperatures – Re-crystallisation of the rocks • High Pressure – minerals re-align causing a change in texture