10 questions · about 3 min · free
Igneous, Sedimentary or Metamorphic?
Sort ten real rocks into the three rock types. Every answer explains how that rock formed.
10 questions · about 3 minutes
Questions are drawn from a pool of 80, so every attempt is different.
Every rock on Earth belongs to one of three families. Igneous rocks cooled from molten magma or lava. Sedimentary rocks were pressed together from sand, mud, shells or dissolved minerals. Metamorphic rocks started as one of the other two and were transformed by heat and pressure without melting.
This quiz shows you ten rocks from the StoneSnap catalog (80 in the pool) and asks which family each belongs to. Each answer explains the formation story, which is the real trick to remembering the type.
The three rock types in one minute
Igneous rocks form from cooling melt. Slow cooling underground makes large crystals (granite, gabbro); fast cooling at the surface makes fine grains or glass (basalt, rhyolite, obsidian, pumice). If you can see interlocking crystals and no layers, think igneous.
Sedimentary rocks form in layers from deposited material: sand becomes sandstone, mud becomes shale, shells and coral become limestone, gravel becomes conglomerate. Look for layers, rounded grains, fossils and a tendency to crumble.
Metamorphic rocks are the changed ones. Limestone becomes marble, sandstone becomes quartzite, shale becomes slate then schist then gneiss, granite becomes gneiss. Look for wavy bands, aligned mica flakes and a crystalline sparkle with no fossils.
The ones everyone gets wrong
Quartzite looks like sandstone but is metamorphic (the grains have fused). Obsidian looks nothing like other igneous rocks because it is glass. Marble and limestone are both calcium carbonate and both fizz in acid, but marble is metamorphic and sparkles with interlocking crystals. Slate is metamorphic even though it splits into flat sheets like a sedimentary rock.
- Browse all igneous rocks in the catalog: /rocks/igneous-rocks
- Browse all sedimentary rocks: /rocks/sedimentary-rocks
- Browse all metamorphic rocks: /rocks/metamorphic-rocks
Frequently asked questions
What are the three types of rocks?
Igneous (cooled from magma or lava), sedimentary (deposited and compacted layers) and metamorphic (existing rock changed by heat and pressure).
Is this quiz suitable for a school rock cycle unit?
Yes. It covers the standard middle-school and high-school earth science content, and every explanation names the parent material and process.
Are minerals igneous, sedimentary or metamorphic?
Neither: those three terms classify rocks, which are made of minerals. A single mineral such as quartz can occur in all three rock types.
