The rock is said to have a fine-grained texture, also referred to as an aphanitic texture.
The size of crystals in an igneous rock is called texture. Texture can range from fine-grained (small crystals) to coarse-grained (large crystals).
Intrusive rock normally has visible crystals. Extrusive igneous rock has small crystals. A black extrusive igneous rock with small crystals could be basalt.
a porphyritic rock. This texture indicates that the rock underwent two stages of cooling: slow cooling deep underground (resulting in the large crystals) followed by faster cooling near the surface (resulting in the small crystals).
The rock is called porphyry, which forms when magma slowly cools beneath the Earth's surface. The large crystals are known as phenocrysts, and the smaller surrounding crystals are called groundmass or matrix.
The rock is said to be extrusive or possess an aphanitic texture, as a result of relatively rapid cooling.
Ah, a classic. It is porphyritic. The classic example is granite.
The size of the crystals is a function of the rate of cooling of the molten rock. The faster the molten rock cools, the smaller the crystals will be.
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.
Small crystals are called microcrystals. These tiny structures are often too small to be seen or examined without the aid of a microscope.
Andesite is an Igneous Rock. It has small crystals because it cooled quickly d;D
The size of the crystals in an igneous rock tells us how fast the magma cooled.
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