3 Part Cards -Kinds of Rocks

. Smooth, black and glassy. An igneous rock with very sharp edges formed where it has been broken. Very useful for making cutting tools .

Obsidian

Obsidian

Rough, light grey, and full of holes. An igneous rock that is very light because it is full of gas bubbles. A rock that can float on water!

Pumice

Pumice

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Rough, blue-grey, with a mixture of small and larger crystals. An igneous rock formed from cooled lava. Also known as “Bluestone”, it is a very useful building material.

Basalt

Basalt Very obvious white, black and pink crystals. An igneous rock formed from cooled magma. Beautiful when polished, it is used for memorials like gravestones.

Granite

Granite

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Brown and looking very smelly. Formed when lava has been extruded through narrow openings. It doesn’t matter if you step in this igneous doggy-do, because it’s rock hard!

Ropy Lava

Ropy Lava

A mixture of sand and pebbles cemented together. This sedimentary rock was formed when a strong flood washed out all sizes of material .

Conglomerate

Conglomerate

. Dark grey with very fine crystals. This metamorphic rock has formed from siltstone that was originally black oozy mud found in swamps.

Shale

Shale Light coloured and very crumbly. This sedimentary rock is quite young and has not had time to cement together properly, so it is too soft and weak to be of any use to us.

Siltstone

Siltstone

Yellow, with obvious sand-sized crystals cemented together. The most common sedimentary rock, it is still being formed today wherever a river is spilling silty water into the sea. .

Sandstone

Sandstone Mud-coloured with obvious layers. This sedimentary rock shows how floods have washed through a variety of landscapes, depositing slightly different sands each time.

Layered Sandstone

Layered Sandstone

Creamy coloured and often full of fossil shells. This sedimentary rock formed from layers of calcareous material floating down from dead, shelled sea creatures above. .

Limestone

Limestone Pure white and very soft. When layers of tiny shells rain down onto the sea bed in clean water, this sedimentary rock results. A teacher’s best friend before whiteboards!

Chalk

Chalk

Light coloured and with an obvious cell structure. This sedimentary rock is the fossilised remains of calcium carbonate that has been organised by a colony of sea creatures called polyps. .

Coral

Coral

Pink and crystalline. This sedimentary rock formed when an ancient sea full of red algae evaporated. Crushed up, it will end up from dining room tables to aluminium smelters!

Rock salt

Rock salt

Bluish and crystalline, with delicate lines and patterns. This rock has metamorphosed from limestone under great pressure and heat. Highly valued for decorating buildings and bathrooms

Marble

Marble

White and crystalline. This rock has metamorphosed from sandstone. Extremely hard, and when the pressure has been high enough, it can be a clear crystal.

Quartzite

Quartzite

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Obsidian

Pumice

Basalt

Granite

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Ropy Lava

Layered Sandstone

Conglomerate

Chalk

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Shale

Marble

Sandstone

Quartzite

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Limestone

Coral

Siltstone

Rock salt

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