Wiki source code of Dolerite
Last modified by Roelof Zwaan on 2021/09/30 15:18
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| 9 | Dolerite is a medium grained mafic intrusive rock and it is sometimes called diabase. It has some similarity with [[basalt>>doc:Environmental Surveys.Rock types.Igneous rocks.Extrusive igneous rocks.Basalt.WebHome]], but on this type of rock the crystals can be spotted with a hand lens. Dolerite has also a similar composition to [[gabbro>>doc:Environmental Surveys.Rock types.Igneous rocks.Intrusive igneous rocks.Gabbro.WebHome]], but gabbro has larger crystals. Dolerites can be found in sills, dikes, lopoliths or laccoliths which cooled slowly. | ||
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| 13 | = Characteristics = | ||
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| 15 | Dolerite is made up from feldspar and pyroxene minerals. The feldspar can be present in a fraction varying from 40 to 70 percent of the rock. Moreover some olivine can be present giving this grey to black rock a greenish glow. Dolerite is an intrusive rock which means phenocrysts can be present. This are large crystals suspended in a matrix of fine crystals. These are present due to mixing of other rocks into the cooling parent magma. The formation of dolerite has two requirements, namely: | ||
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| 17 | * A basaltic magma source | ||
| 18 | * Shallow emplacement and cooling in a relatively small subsurface structure such as a sill, dike, lopolith or laccolith. | ||
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| 20 | = References = | ||
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| 22 | * [[https:~~/~~/geology.com/>>url:https://geology.com/]] | ||
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| 29 | = Dolerite = | ||
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| 31 | [[image:Dolerite.jpg||alt="image.jpg"]] | ||
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| 34 | |=Type|Extrusive igneous rock | ||
| 35 | |=Clasts|Medium grained | ||
| 36 | |=Hardness|((( | ||
| 37 | Very hard | ||
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| 39 | |=Color|grey to black with greenish luster | ||
| 40 | |=Minerals|Feldspar and pyroxene minerals | ||
| 41 | |=Touch|Rough | ||
| 42 | |=Image|[[Dolerite >>url:https://www.google.com/url?sa=i&url=https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FDiabase&psig=AOvVaw1Yn-tJ917J4DEgm15CvrBn&ust=1610451056748000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCIC9uu7jk-4CFQAAAAAdAAAAABAJ]] | ||
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| 47 | **Contents** | ||
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| 49 | {{toc/}} | ||
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