Non-Skeletal Grain types

Non Carbonate Grains

1. Quartz

Oyster bivalve packstone/rudstone with medium sand size quartz grains (angular white transparent grains in parallel polarisers) in the carbonate matrix.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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2. Quartz

Previous image of oyster bivalve packstone with medium sand size monocrystalline quartz grains in the carbonate matrix in crossed polarisers showing the typical grey to white/yellow birifrangence of the quartz minerals.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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3. Quartz

Skeletal condensed packstone with a composite quartz grain (polycrystalline detrital quartz) deriving from eroded metamorphic tary rocks associated with dasyclad algae (image in crossed polarisers, Eocene).

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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4. Phosphate

Porous foraminiferal (Nummulites), bryozoan and red algae grainstone with a brown colour phosphatic grain.

Oligocene, Central Apennine, Italy

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5. Phosphate

Planktonic foraminifera packstone with sparse brown/yellow phosphatic grains.

Oligocene, Central Apennine, Italy

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6. Glaucony

Planktonic foraminifera (Orbulina, Globegerinoides) packstone/wackestone with sparse green glaucony grains.

Lower Miocene, Central Apennine, Italy

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7. Glaucony

Compacted skeletal packstone with larger benthic foraminifers, rotalids and red algae fragments. On the right side, green colour glaucony grains. Glaucony is also impregnating the Amphistegina foraminifer in the centre left.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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8. Glaucony

Previous image viewed in crossed polarized light. Compacted skeletal packstone with larger benthic foraminifers, rotalids and red algae fragments. On the right side, green colour glaucony grains. Glaucony is also impregnating the Amphistegina foraminifer in the centre left.

Thin section kindly provided by T. Geel, Vrije Universiteit, Amsterdam

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detrital quartz grain

oyster

detrital quartz grain

polycrystalline quartz grain

dasyclad alga

phosphatic grain

Nummulites

phosphatic grain

planktonic foraminifera

planktonic foraminifer Orbulina

glaucony

Amphistegina

glaucony

Amphistegina

glaucony

Non Carbonate Grains

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detrital quartz grain

oyster

detrital quartz grain

polycrystalline quartz grain

dasyclad alga

phosphatic grain

Nummulites

phosphatic grain

planktonic foraminifera

planktonic foraminifer Orbulina

glaucony

Amphistegina

glaucony

Amphistegina

glaucony