Igneous rocks form when magma (within Earth's surface) or lava (at Earth's surface)
cool to a solid form.
The solidification occurs at different speeds and with different modalities, and different texture result as a consequence.
1 
PHANERITIC TEXTURE
Crystals are visible to the naked eye (0.1 to 1 cm) slow cooling, viscous magma
granite |
2  APHANITIC TEXTURE Crystals are not visible to the naked eye (less than 0.1 cm) rapid cooling, fluid lava
rhyolite |
3  PEGMATITIC TEXTURE Crystals are very big in size (> 1 cm) very slow cooling, viscous magma
pegmatitic granite |
4 
FROTHY TEXTURE rock looks like a meringue rapid cooling of gas-rich lava pumice |
5  GLASSY TEXTURE rock looks and breaks like a glass extremely rapid cooling, minerals have no time to form obsidian |
6  GLASSY TEXTURE rock looks and breaks like a glass extremely rapid cooling, minerals have no time to form obsidian |
7  PORPHYRITIC TEXTURE Large and small crystals are found together
cooling changed from slow to rapid porphyritic andesite |
8  PORPHYRITIC TEXTURE Large and small crystals are found together
cooling changed from slow to rapid porphyritic andesite |
9  VESICULAR TEXTURE Small bubbles and cavity dot the rock surface bubbles of gas left the magma during solidification vesicular basalt |
