Small crystal grains form when molten rock cools quickly. In an extrusive igneous rock, it's referred to as aphanitic texture.
Fine crystal grain.
lava
the grain of zircon and it is the width of a human hair
plagioclase, microcline, rhodonite, turquoise, wollastonite, amblygonite, and many more.
No, intrusive rocks are typically coarse-grained because they form from magma that cools slowly beneath the Earth's surface, allowing larger crystals to develop. In contrast, extrusive rocks, which form from lava that cools quickly on the surface, are usually fine-grained. Thus, the grain size is a key distinguishing feature between intrusive and extrusive igneous rocks.
Fine crystal grain.
Fine
lava
Large crystals with a coarse crystal grain texture.
Small crystal grains form from rapid cooling of magma resulting in an aphanitic rock texture.
It is mineral
When molten rock cools quickly, fine-grained crystals form. This happens because there is not enough time for larger crystals to grow before the rock solidifies, resulting in smaller crystals being formed.
The texture of the rock product of slow cooling magma is referred to as coarse grained.
Quartz
When molten rock cools slowly, it will have a lot of time to form crystals, so the crystal size will be quite big. Take granite, for example. With the naked eye, you can see the individual crystals. The grain size is quite large. The kind of mineral that forms is dependent on the composition of the magma.
the crystals are large
Visible or coarse.