If you're not looking for anything specific, any extrusive igneous rock will have smaller crystals, if any at all. This is because they cool quickly on the surface, leaving little time for crystals to form/grow.
The size of the crystals in an igneous rock tells us how fast the magma cooled.
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.
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The texture depends on the size and shape of the crystals you see in it. The larger the crystals, the slower the rate of cooling. This suggests that it is an intrusive rock. Smaller crystals suggest more rapid cooling indicating that it is an extrusive rock. INTRUSIVE- cooled inside the earth and had more time to create crystals EXTRUSIVE- cooled on the surface of the earth and created small crystals
The rock is said to be extrusive or possess an aphanitic texture, as a result of relatively rapid cooling.
Intrusive rock normally has visible crystals. Extrusive igneous rock has small crystals. A black extrusive igneous rock with small crystals could be basalt.
The size of the crystals in an igneous rock tells us how fast the magma cooled.
Igneous rocks can have both small and large crystals, depending on how quickly they cool. If an igneous rock cools slowly beneath the Earth's surface, it can form large crystals, while rapid cooling at the Earth's surface or in an eruption can result in small or no visible crystals.
Small
small crystals
You would expect to find an igneous rock with small crystals near the Earth's surface where the rock cools relatively quickly, such as in volcanic eruptions or magma intrusions that do not have much time to grow large crystals. These rocks are known as volcanic or extrusive igneous rocks.
The size of crystals in an igneous rock is called texture. Texture can range from fine-grained (small crystals) to coarse-grained (large crystals).
Andesite is an Igneous Rock. It has small crystals because it cooled quickly d;D
Small ones.
Rhyolite.
by the size of the crystals, big crystals intrusive, small crystals extrusive
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.