What kind of metamorphic rock is quartzite

Such conditions fuse the quartz grains together forming a dense, hard, equigranular rock. The name quartzite implies not only a high degree of induration hardness , but also a high quartz content. As a result, typically-quarried quartzite is very near the surface. Because it is so hard and dense, quartzite has not been quarried as extensively as other softer dimension stone such as limestone, sandstone and granite.

Since quartzite breaks into flat surfaces, it is used as a dimension stone in the construction industry, for decorative stone in building construction and for some aggregates. Paleolithic humans sometimes made stone tools out of quartzite, although it was harder to work than flint or obsidian. Quartzite is a metamorphic rock, while quartz is an igneous rock that crystallizes from magma or precipiates around hydrothermal vents.

Sandstone under pressure becomes quartz arenite and quartzite, but quartzite does not become quartz. The construction industry further complicates the matter. If you buy "quartz" for countertops, it is actually an engineered material made from crushed quartz, resin, and pigments and not the natural rock. Another rock commonly confused with quartzite is marble. Both quartzite and marble tend to be pale-colored, non-foliated rock. Despite having a similar appearance, marble is a metamorphic rock made from recrystallized carbonate minerals, not silicates.

Marble is softer than quartzite. An excellent test to distinguish the two is to apply a bit of vinegar or lemon juice to the rock. Quartzite is impervious to weak acid etching, but marble will bubble and retain a mark. Actively scan device characteristics for identification. Use precise geolocation data. Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads.

Apply market research to generate audience insights. Measure content performance. If the original limestone was pure calcite, then the marble will likely be white as in Figure 7. Quartzite is metamorphosed sandstone Figure 7. It is dominated by quartz, and in many cases, the original quartz grains of the sandstone are welded together with additional silica. Most sandstone contains some clay minerals and may also include other minerals such as feldspar or fragments of rock, so most quartzite has some impurities with the quartz.

On the other hand, any clay present in the original sandstone is likely to be converted to mica during metamorphism, and any such mica is likely to align with the directional pressure. An example of this is shown in Figure 7. The quartz crystals show no alignment, but the micas are all aligned, indicating that there was directional pressure during regional metamorphism of this rock.

Hornfels is another non-foliated metamorphic rock that normally forms during contact metamorphism of fine-grained rocks like mudstone or volcanic rock Figure 7.

In some cases, hornfels has visible crystals of minerals like biotite or andalusite. If the hornfels formed in a situation without directed pressure, then these minerals would be randomly orientated, not foliated as they would be if formed with directed pressure. Skip to content Chapter 7 Metamorphism and Metamorphic Rocks. Exercise 7. The mica crystals are consistently parallel to one another. A very hard rock with a granular appearance and a glassy lustre. There is no evidence of foliation.