Ways to use this list
- Rock kit match-up: spin, then find that sample in the class rock kit and test it with a steel nail. If the nail leaves a scratch, the rock is softer than steel.
- Rock cycle story: spin a rock and tell its life story. Limestone can be buried, heated into marble, pushed up into a mountain and worn down into sand again.
- Town rock walk: spin a few rocks before a walk and hunt for them in buildings and streets, such as granite kerbs, slate roofs, sandstone walls and marble statues.
- Three-family quiz: spin, and everyone holds up a card marked I, S or M for igneous, sedimentary or metamorphic. Check with the buttons above.
- Fossil talk: spin until a sedimentary rock comes up, then discuss why fossils turn up in limestone and shale but almost never in granite.
Press Spin the wheel, tap the game or press the Space bar. Change the list in the box as you
like: add your own, delete what doesn't suit you, or write *2 after an entry to give it double the
chance. The game buttons switch the same list to a duck race, hat, claw machine and more.
The full list (28 entries)
- Granite – igneous: speckled and tough, cooled slowly underground
- Basalt – igneous: dark lava rock that makes up most of the ocean floor
- Obsidian – igneous: black volcanic glass
- Pumice – igneous: so full of air holes that it floats
- Gabbro – igneous: dark and coarse-grained, cooled underground
- Diorite – igneous: salt-and-pepper speckles
- Andesite – igneous: grey lava rock named after the Andes
- Rhyolite – igneous: pale lava rock with the same minerals as granite
- Scoria – igneous: red or black lava rock full of holes
- Tuff – igneous: volcanic ash squashed into rock
- Sandstone – sedimentary: grains of sand cemented together
- Limestone – sedimentary: often made of old shells, fizzes in acid
- Chalk – sedimentary: soft white limestone made of tiny sea plankton
- Shale – sedimentary: hardened mud that splits into thin layers
- Mudstone – sedimentary: hardened mud that breaks into blocks
- Conglomerate – sedimentary: rounded pebbles stuck together
- Breccia – sedimentary: sharp, broken pieces stuck together
- Coal – sedimentary: made from plants of ancient swamps
- Rock salt – sedimentary: left behind when salty water dried up
- Chert – sedimentary: very hard; flint is a kind of chert
- Marble – metamorphic: limestone changed by heat and pressure
- Slate – metamorphic: shale changed into flat sheets for roofs
- Schist – metamorphic: sparkly with flat flakes of mica
- Gneiss – metamorphic: striped in light and dark bands, said "nice"
- Quartzite – metamorphic: sandstone changed into a very hard rock
- Phyllite – metamorphic: between slate and schist, with a silky shine
- Hornfels – metamorphic: baked hard by nearby hot magma
- Soapstone – metamorphic: soft enough to scratch with a fingernail
Questions people ask
What are the three types of rock?
Igneous rock forms when hot melted rock (magma or lava) cools and hardens. Sedimentary rock forms from layers of sand, mud or shells pressed and cemented together. Metamorphic rock is any rock changed by great heat and pressure deep underground.
How can I tell different rocks apart at home?
Look for crystals, layers and holes, and feel whether it is gritty like sandstone. Then try a few drops of vinegar: limestone, chalk and marble fizz, because they are made of the mineral calcite. Most other rocks stay quiet.
Is there a rock that floats on water?
Yes, pumice. It forms when frothy lava full of gas cools so quickly that the bubbles are trapped inside, leaving the rock so light that it floats. Rafts of pumice have drifted across oceans after big eruptions.
What is the difference between a rock and a mineral?
A mineral is a natural solid with a fixed chemical recipe and crystal shape, such as quartz. A rock is a mix of one or more minerals: granite is mostly quartz, feldspar and mica. Many gems are minerals, as the random gemstone generator shows.