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Uses of Diorite
In areas where diorite occurs near the surface, it is sometimes mined for use as a crushed stone. It has a durability that compares favorably to granite and trap rock. It is used as a base material in the construction of roads, buildings, and parking areas. It is also used as a drainage stone and for erosion…
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Diorite and Andesite
Diorite and andesite are similar rocks. They have the same mineral composition and occur in the same geographic areas. The differences are in their grain sizes and their rates of cooling. Diorite crystallized slowly within the Earth. That slow cooling produced a coarse grain size. Andesite forms when a similar magma crystallizes quickly at Earth’s surface. That rapid cooling produces…
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What is Diorite?
Diorite is the name used for a group of coarse-grained igneous rocks with a composition between that of granite and basalt. It usually occurs as large intrusions, dikes, and sills within continental crust. These often form above a convergent plate boundary where an oceanic plate subducts beneath a continental plate. Partial melting of the oceanic plate produces a basaltic magma that…
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Uses of Diabase
Most diabase that is mined is used in the construction industry. There are several types of use: 1) Crushed Stone: Diabase is one of many types of “trap rock” used as crushed stone in the construction industry. These are durable rocks that have many uses. For most of these uses, the aggregate must meet certain specifications of abrasion…
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Geologic Occurrence of Diabase
The formation of diabase has two requirements: 1) a basaltic magma source 2) shallow emplacement and cooling in a relatively small subsurface structure such as a sill, dike, lopolith or laccolith.
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Problems Identifying Diabase
The fine-grained texture of diabase makes identification in the field or in a classroom a difficult undertaking. The observer must have enough skill to view the physical properties of tiny mineral grains, and enough knowledge to identify the minerals. Getting a confident identification in these locations can be difficult. Diabase is best identified in thin…
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Diabase Porphyry
Some igneous rocks have a complex cooling history that results in them containing grains of distinctly different crystal sizes. These rocks, with large crystals (known as “phenocrysts”) suspended in a matrix of fine crystals (known as “groundmass”), often have a cooling history similar to the following description: The parent magma of the rock began cooling…
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Mineral Composition of Diabase
Diabase typically has a mineral composition that is dominated by the plagioclase feldspar known as labradorite (approximately 40% to 70% of the rock). Most of the remainder is made up of pyroxene minerals (usually augite). Minor amounts of hornblende, olivine, magnetite, and quartz can be found in some diabase rocks. Although the mineral species present in diabase often have perfect cleavage, when they are present in tiny interlocking grains,…
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Diabase
Stonehenge is one of the most famous stone structures ever made by humans. Stones of the monument’s inner circle are made of diabase. They were transported about 240 miles from Wales to the monument site in England in about 2100 BC. What is Diabase? In the United States and Canada, the name “diabase” is used for…
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Blackboards and Chalk
Small pieces of chalk have been used by students for over 1000 years for writing on small slates and large classroom panels known as “blackboards”. It is an inexpensive and erasable writing material and the most widely known use of chalk. Much of the early blackboard writing was done with pieces of natural chalk or…