Rock Chart

Magma Types

Ultramafic Melts

• Formation: Ultramafic melts form magic magma.
• **Features: **
  • Composed predominantly of mafic minerals.
  • Associated with high-temperature environments, typically formed in the lower parts of the Earth's mantle.

Intrusive Gabbro

• Composition: Coarse-grained, composed of mafic minerals.
• Location: Primarily found in oceanic crust and lower continental crust.

Diorite

• Composition: Intermediate rock, with a mix of mafic and felsic minerals.
• Location: Typically occurs in the middle of the continental crust.

Felsic Intrusive Rocks

• Features: Coarse-grained and primarily composed of felsic minerals, such as quartz and feldspar.
• Common Examples: Granitic rocks.

Extrusive Rocks

Basalt

• Composition: Mafic in nature, consisting mainly of iron and magnesium silicates.
• Location: Commonly found in oceanic crust.
• Formation: Often originates from hot spots and convergent plate boundaries where tectonic activity is present.
  • Typical Texture: Generally porphyritic, with larger crystals embedded in a finer-grained matrix.

Volcanic Rocks

• Characteristics: Form from eruptions of hot magma that cools rapidly at the surface.
• Types:
  • Mafic Fragmented Rocks: Formed from the explosive eruption of magma containing a significant amount of gas.
  • Glassy Felsic: Produced by rapid cooling of magma, resulting in a glassy texture.
  • Tuffs: Composed of volcanic ash and fragments that accumulate around the vent of a volcano.
  • Pyroclastic Rocks: Formed from explosive volcanic activity that fragments magma into various sizes.

Pumice

• Composition: Felsic volcanic rock that is typically light in color and has a frothy texture due to gas bubbles trapped during formation.
• Features: Vesicular texture, often used for abrasives and in horticulture.

General Types of Magma

• Mafic: Rich in iron and magnesium, lower in silica content.
• Felsic: Higher in silica content, rich in quartz and feldspar.