Basalt Granite And Obsidian Rock

Igneous rocks that solidified within the crust are plutonic or intrusive rocks.

Basalt granite and obsidian rock.

The hardness of basalt is 6 and that of obsidian is 5 5 5. Basalt is a dark colored fine grained igneous rock composed mainly of plagioclase and pyroxene minerals. Dacite is an extrusive igneous rock. Igneous rocks from left to right.

The canadian shield of north america contains huge outcroppings surface rocks of granite. Gabbro andesite pegmatite basalt pumice porphyry obsidian granite and tuff. Basalt is an extrusive or intrusive rock that makes up most of the world s oceanic crust. Molten rock material below the surface is called magma.

Associate each rock name granite diorite gabbro rhyolite andesite basalt obsidian pumice scoria tuff and volcanic breccia from the classification chart with the geological setting numbers 1 12 shown on the following diagram. The principle minerals that make up dacite are plagioclase quartz pyroxene or hornblende. It most commonly forms as an extrusive rock such as a lava flow but can also form in small intrusive bodies such as an igneous dike or a thin sill it has a composition similar to gabbro the difference between basalt and gabbro is that basalt is a fine grained rock while. Magma that has reached the surface is lava.

Basalt is available in black brown light to dark grey colors whereas obsidian is available in black blue brown green orange red tan yellow colors. Appearance of basalt is dull and soft and that of obsidian is shiny. When obsidian breaks it fractures with a distinct conchoidal fracture. Basalt is fine grained so the individual minerals are not visible but they include pyroxene plagioclase feldspar and olivine these minerals are visible in the coarse grained plutonic version of basalt called gabbro.

Obsidian is a very shiny natural volcanic glass.