Volcanic Rock (Igneous)

Volcanic Rock (Igneous) Definition

A “Volcanic Rock” is an igneous rock that is finely crystalline and glassy (or aphanitic). To illustrate, volcanic rocks result from volcanic action at the earth’s surface. Typically, this also includes igneous intrusions that are “near-surface,” which may otherwise be considered plutonic. This action results in a final rock that is different in consistency, texture, and formation, comparing to other igneous rocks that crystalize underground. Moreover, most volcanic rocks are violently ejected or calmly extruded in the form of lava (liquid phase rock).

Examples of Volcanic Rock Types in Igneous Rock Classification

  • alkali-feldspar rhyolite
  • rhyolite (liparite)
  • dacite
  • quartz-alkali (-feldspar) trachyte
  • alkali (-feldspar) trachyte
  • foid-bearing alkali (-feldspar) trachyte
  • quartz trachyte
  • trachyte
  • foid-bearing trachyte
  • quartz latite
  • latite
  • foid-bearing latite
  • andesite
  • calc-alkaline andesite
  • andesite
  • mugearites
  • basalt
  • tephritic phonolite
  • phonolite tephrite (basanite)
  • tephrite
  • basanite
  • phonolitic foidite
  • tephritic foidite
  • foidite

Similar Posts

  • Poorly Graded

    ByGeo Forward

    Poorly Graded Soil Poorly Graded: In the soil classification process of geology, poorly graded soil represents a sedimentary soil sample that only displays one or a few of the numerous other possible grain sizes for that soil classification, in accordance with the Unified Soil Classification System (USCS). For example, a poorly graded sand (SP) may…

  • Effective Stress (σ’)

    ByGeo Forward

    Effective Stress (σ’) “Effective Stress” (σ’) is a geotechnical engineering term. Effective Stress is a function of “total stress,” and is due to the solid particles of soil. Effective stress represents an excess of stress above pore-water pressure (or neutral stress). Effective Stress Formula Effective Stress = Total Stress – Pore-Water Pressure.

  • Growth Fault

    ByGeo Forward

    Growth Fault Growth Fault: In geology, a growth fault is a strike-slip fault or dip-slip fault that moves contemporaneously with deposition. This causes the throw (amount of vertical displacement) to increase with depth and the strata to be thicker on the downthrown side as compared to the upthrown side.

  • Effective Size (D10)

    ByGeo Forward

    Effective Size (D10) “Effective Size” (D10) is an engineering geology term. Effective Size represents a diameter that directly corresponds to the percentage, by weight, of grains that equal to 10% on the grain-size diagram. To illustrate, 10% of the soil sample particles are finer-grained, and 90% of the sample particles are coarser than the “effective…

  • Mineraloid

    ByGeo Forward

    Mineraloid Definition The term “mineraloid” refers to a natural earth substance that appears to be similar to a genuine mineral, although lacks any form of internal structure and crystal form. Nonetheless, a mineraloid does comprise true minerals within it. For instance, Fire Opal and Blue Opal are not minerals because they are amorphous (do not…