Sedimentary Rocks A Virtual Practical I.G.Kenyon

The following slides are all sedimentary rocks From the information displayed Decide if the rock is: clastic, organic or chemical Identify each rock as accurately as possible Suggest a sedimentary environment in which it may have formed

Identify this Sedimentary Rock 1 1cm Poorly Sorted 40% Muddy Matrix Rock Fragments Mineral Grains

Identify this Sedimentary Rock 2 Reacts with dilute hydrochloric acid Comprises over 70% broken bivalve shells Remainder of rock is silt and iron oxides 2cm

Identify this Sedimentary Rock 3 2cm Comprises entirely clay minerals and carbonaceous material Well preserved graptolites are found in the rock Splits into thin layers easily (Fissile)

Identify this Sedimentary Rock 4 1cm Reacts with dilute hydrochloric acid Comprises entirely of spherical grains 0.5–1.0mm in diameter

Identify this Sedimentary Rock 5 Made up entirely of clay minerals such as kaolinite, illite and bentonite Homogenous or massive with no trace of bedding or laminations 1cm

Identify this Sedimentary Rock 6 4cm Comprises angular fragments 0.5mm – 8cm in diameter All parts of the rock react with dilute hydrochloric acid

Identify this Sedimentary Rock 7 5mm Comprises mainly sub angular quartz and feldspar grains 20% of the rock has fragments 2 - 4mm in diameter

Identify this Sedimentary Rock 8 Fibrous appearance Very low density Clearly visible remains of organic matter Rich in carbon 1cm

Identify this Sedimentary Rock 9 2cm Composed entirely of silica Broken surfaces show conchoidal fracture

Identify this Sedimentary Rock 10 1cm Comprises some clay minerals such as kaolinite and illite Has a gritty feel when rubbed on the teeth, >10% quartz present

Identify this Sedimentary Rock 11 Well rounded flint pebbles 8mm – 6cm in diameter Cement does not react with dilute hydrochloric acid

Identify this Sedimentary Rock 12 1cm Rich in carbon, makes a black mark on paper No recognisable traces of organic material evident

Identify this Sedimentary Rock 13 1cm Grain size <1/256mm Comprises almost entirely clay minerals, chiefly kaolinite No bedding or laminations evident. Plastic when wet

Identify this Sedimentary Rock 14 1cm Comprises well rounded quartz grains 0.25 – 0.5mm in diameter Weak iron oxide cement-crumbles in the fingers (friable)

Identify this Sedimentary Rock 15 Fossil replaced by flint 2cm Reacts with dilute hydrochloric acid Rock is made up of coccoliths

Identify this Sedimentary Rock 16 1cm Reacts with dilute hydrochloric acid Made up mainly of broken crinoid stems

Identify this Sedimentary Rock 17 1cm Comprises entirely well rounded quartz grains 0.25–0.75mm in diameter Very well cemented together by silica

Identify this Sedimentary Rock 18 1cm Reacts with dilute hydrochloric acid Comprises angular fragments 0.5mm – 5cm in diameter

Identify this Sedimentary Rock 19 Comprises angular to sub angular grains of quartz and feldspar Contains more than 25% feldspar Iron oxide cement 1cm

Identify this Sedimentary Rock 20 Particle size varies from 1mm – 4cm Comprises fragments of limestone, basalt, slate and quartz All particles are angular Red iron oxide cement 1cm

Identify this Sedimentary Rock 21 1cm Comprises quartz and muscovite grains Splits readily into slabs 3-6cm thick

Identify this Sedimentary Rock 22 1cm Reacts with dilute hydrochloic acid Made up entirely of angular shell fragments 0.5-3mm

Identify this Sedimentary Rock 23 Has a woody ‘ring’ to it when tapped Rich in carbon Low density Organic structure clearly visible 1cm 1cm

Identify this Sedimentary Rock 24 2cm Made up entirely of hydrated calcium sulphate This variety is called Desert Rose

Identify this Sedimentary Rock 25 Mica flakes concentrated on lamination surfaces 1cm Contains some clay minerals, chiefly kaolinite Over 10% quartz present plus mica flakes Feels gritty when rubbed on the teeth

Identify this Sedimentary Rock 26 Jet black colour Contains over 95% carbon Vitreous lustre Marks paper No recognisable traces of any organic matter 1cm

Identify this Sedimentary Rock 27 2cm Made up entirely of clay minerals, chiefly kaolinite No obvious laminations or bedding present Contains well preserved trilobite pygydium

Identify this Sedimentary Rock 28 2cm 2cm Reacts with dilute hydrochloric acid Has an internal concentric banded structure Specimen obtained from the roof of a limestone cave

Identify this Sedimentary Rock 29 Majority of clasts are rounded to well rounded Poorly sorted, grain size varies <1mm to 10cm

Identify this Sedimentary Rock 30 Composed entirely of sodium chloride Occurs in thin, near horizontal beds Often grey, white colourless, orange or brown Tastes salty 1cm

Identify this Sedimentary Rock 31 1cm All parts of the rock react with dilute hydrochloric acid Comprises shell fragments, faecal pellets and large ooliths

Identify this Sedimentary Rock 32 1cm Comprised of clay minerals and carbonaceous material Lacks distinct laminations Contains well preserved plant fragment

Identify this Sedimentary Rock 33 1cm Comprises mainly quartz grains <0.25 in diameter Brown colour due to 10-15% clay content Contains external moulds and casts of brachiopods

Identify this Sedimentary Rock 34 Contains a high percentage of sub-rounded to rounded quartz grains Some rock fragments Poorly sorted, particle size ranges from <0.5mm – 1cm Finer matrix makes up 15-20% of the rock No reaction with dilute hydrochloric acid 1cm

Identify this Sedimentary Rock 35 1cm Rich in iron, hence brownish colour (limonite) Cannot be found forming anywhere on earth today

Name this Sedimentary Rock 36 Reacts with dilute hydrochloric acid Contains corals preserved in life position

Identify this Sedimentary Rock 37 Locally known as Haggis Rock 1cm Sub-angular to sub-rounded particles Mixture of rock fragments and quartz grains 0.5mm to 5mm in diameter Matrix consists of mud and silt and makes up over 20% of the rock

Identify this Sedimentary Rock 38 1cm Particle size 1mm up to 8mm, quite poorly sorted Mineralogy mainly sub-angular to sub-rounded quartz and feldspar

Identify this Sedimentary Rock 39 1cm Reacts with dilute hydrochloric acid May contain a small percentage of clay minerals

Identify this Sedimentary Rock 40 1cm Comprises quartz grains 0.25 – 0.75mm in diameter Moderately well cemented by glauconite, a pale green mineral

Answers 1. 1. Greywacke 11. Conglomerate 2. Bioclastic Limestone 12. Bituminous Coal 3. Black Shale 13. Clay 4. Oolitic Limestone 14. Desert Sandstone 5. Mudstone 15. Chalk 6. Limestone Breccia 16. Crinoidal Limestone 7. Millstone Grit 17. Orthoquartzite 8. Peat 18. Limestone Breccia 9. Flint 19. Arkose 10. Siltstone 20. Breccia

Answers 2. 21. Micaceous Sandstone 31. Biochemical Lst. 22. Calcareous sandstone 32. Mudstone 23. Lignite(Brown Coal) 33. Fine Sandstone 24. Rock Gypsum 34. Conglomerate 25. Micaceous Siltstone 35. Ironstone 26. Anthracite 36. Coral Limestone 27. Mudstone 37. Greywacke 28. Tufa 38. Grit 29. Conglomerate 39. Micrite/Marl 30. Rock Salt 40. Orthoquartzite

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