What factor determines the size of the crystals?

What factor determines the size of the crystals?

The factor that affects the size of the crystals is the cooling rate of the molten rock or magma. If the magma cools rapidly, the crystal formed is very small, whereas if the magma cools slowly, the crystal formed is large.

What causes small crystals in metamorphic rock?

During metamorphism, sedimentary or igneous assemblages of minerals become unstable as a result of newly-imposed conditions of temperature and pressure, and the minerals interact to form new assemblages. Hence, crystal growth in metamorphic rocks takes place at temperatures of ca.

How does crystal size change with increasing metamorphic grade?

Note: As the grade of metamorphism increases (more temperature and pressure), both crystal size and the coarseness of foliation increase. Therefore, gneiss represents more intense metamorphism (or a higher grade) than does schist. Some fine-grained metamorphic rocks, e.g. schist, have larger crystals present.

What two factors affect the size of each individual crystal in the rock?

Factors Affecting Crystal Growth Variables that control crystal growth include the amount of dissolved material, evaporation, pressure and temperature. The higher the amount of dissolved material in the water and the more pressure that is placed on the material, the bigger the crystals will grow.

What factors affect crystal size in an igneous rock?

When magma cools, crystals form because the solution is super-saturated with respect to some minerals. If the magma cools quickly, the crystals do not have much time to form, so they are very small. If the magma cools slowly, then the crystals have enough time to grow and become large.

What major factors increase the crystal size of minerals in igneous rocks How?

Textures of Igneous Rocks Igneous rocks are classified according to where magma cools and hardens. The texture of igneous rock is determined by the size of the crystals in the rock. The size of the crystals in determined mainly by the cooling rate of the magma.

How are crystals formed in metamorphic rocks?

In metamorphic rocks grain size is controlled by pressure and temperature (and crystals grow by transformation of existing minerals in the solid state); the higher the temperature and pressure, the coarser the grain size.

Do metamorphic rocks have big crystals?

Metamorphic rocks can exhibit great variation in crystal size; in general, the size of crystals increase as the grade of metamorphism increases. During the recrystallization process, certain metamorphic minerals, including garnet, staurolite, and andalusite, tend to develop a few large crystals [28,29].

How does metamorphic grade affect grain size?

In general, the grain size of metamorphic rocks tends to increase with increasing grade of metamorphism, as seen in the progression form fine grained shales to coarser (but still fine) grained slates, to coarser grained schists and gneisses.

What are the factors that affect the change in a rock during metamorphism?

The main factors that control metamorphic processes are:

• The mineral composition of the parent rock.
• The temperature at which metamorphism takes place.
• The amount and type of pressure during metamorphism.
• The types of fluids (mostly water) that are present during metamorphism.
• The amount of time available for metamorphism.

What are the factors that affect crystallization?

Various factors such as the degree of supersaturation during the process, temperature and cooling curves during the process, seeding, agitation, solvent composition, pH, polarity, and the presence of certain impurities or other additives that inhibit nucleation process have all shown to influence crystallization …