Latite is a volcanic rock that can be gray, yellow, pink, or white. A variety of minerals are often contained within the rock. It typically has very little if any quartz; the content is usually less than 5% in the pure form, while a similar rock called monzonite can consist of 10% or more of quartz. An igneous rock, latite usually forms from hot, fluid material called magma deep within the Earth.
Sometimes the rock can surface during a volcanic eruption, or it can remain below the surface with lava that remains underground. Intrusive rocks from magma can get exposed over time with surface erosion. Latite is sometimes discovered in these types of deposits. The minerals in the rock are often identified using a visual analysis of the rock’s minerals, which is often done by comparing their texture to scientific charts; a chemical analysis can also be performed to confirm the nature of the rock.
Feldspar, olivine, and pyroxene are common minerals seen in latite. If the rock does contain quartz, then generally there is no olivine contained within it. Other common volcanic rocks include basalt and andesite; latite was originally identified in the late 1800s to define its similarity to rocks found in Italy. The feldspar in latite is usually present as large crystals, while feldspar and another mineral called augite make up a finer matrix of material.
Latite can form in the various places igneous rocks do, including where tectonic plates spread out at long ridges below the oceans. It also typically forms at subduction zones where one plate gets pushed below another, as well as where the Earth’s outer crust gets pushed together. Pressure and heat often alter rock formations in these locations. One characteristic typically seen in this rock is the presence of large crystals of minerals. Large grains of these are called phenocrysts; a rock that has these is referred to as a porphyry.
Common igneous rocks include basalt, which typically forms under the oceans, and granite, found on land. Latite is generally found on land and is common in the western part of North America. While several different minerals are common to it, the actual content of each rock can vary, and there can be a variety of textures as well. The rock can be analyzed using several scientific methods, and small samples viewed under a microscope, with polarized light, is one way of viewing individual crystals within a sample.
