Does diabase have crystals?

The large crystals, called phenocrysts, in diabase are feldspar crystals that grew as the magma cooled slowly deep in a magma chamber.

What minerals are in diabase?

Diabase is dense, hard, and sparsely fractured. It is composed mostly of plagioclase (An50-70), clinopyroxene (mostly augite) and magnetite +/- ilmenite. Accessory minerals include apatite, quartz, alkali feldspar, hornblende, titantite, and zirocon. Olivine is rare.

What is unique about diabase?

Unique features to look for: Very fine grains, very dark color. Figure 3: The diabase in close-up. Note that no distinct minerals are visible. There is a surface pattern that shows how the iron-rich and crumbly diabase is continuing to break down through weathering. Black ballpoint pen for scale.

What are some uses of diabase?

Diabase is crushed and used as a construction aggregate for road beds, buildings, railroad beds (rail ballast), and within dams and levees. Diabase can be cut for use as headstones and memorials; the base of the Marine Corps War Memorial is made of black diabase “granite” (a commercial term, not actual granite).

Is diabase the strongest rock?

The strongest rock in the world is diabase, followed closely by other fine-grained igneous rocks and quartzite. Diabase is strongest in compression, tension, and shear stress. If mineral hardness is the determining factor of strength then diamond is technically the strongest rock in the world.

Why is diabase an igneous rock?

Diabase Porphyry The parent magma of the rock began cooling slowly, deep underground, and some large crystals of minerals with a high crystallization temperature began to form there.

Is diabase the hardest rock?

How strong is diabase?

How to Define Rock Strength

What is the hardness of diabase?

Is diabase a volcanic?

Diabase, also called Dolerite, fine- to medium-grained, dark gray to black intrusive igneous rock. Chemically and mineralogically, diabase closely resembles the volcanic rock basalt, but it is somewhat coarser and contains glass. With increase in grain size, diabase may pass into gabbro.

What is the difference between basalt and diabase?

Diabase is actually a variety of gabbro which consists mainly of labradorite feldspar, augite, magnetite, and olivine. Basalt is identical to diabase and gabbro, but is very fine-grained. Basalt is from a melt that cooled very rapidly- in other words, on the surface of the earth or in the ocean.

What kind of minerals are found in diabase rocks?

Minerals of lesser importance are magnetite, olivine, ilmenite, hornblende, biotite, chlorite, etc. The term “diabase” has a long and complicated history. It was first defined by a French geologist Alexandre Brongniart in 1807. Brongniart named so rocks that were composed of feldspar and hornblende.

What makes up dolerite and diabase igneous rocks?

Diabase is composed of plagioclase feldspar (mostly labradorite) and pyroxene ( augite ). The crystals that make up dolerite are usually visible to the naked eye, but sometimes porphyritic rocks of basaltic composition with pyroxene and especially plagioclase phenocrysts are also named that way.

Which is a characteristic feature of diabase igneous rocks?

The crystals that make up dolerite are usually visible to the naked eye, but sometimes porphyritic rocks of basaltic composition with pyroxene and especially plagioclase phenocrysts are also named that way. Ophitic texture (randomly oriented plagioclase laths enclosed by pyroxene grains) is a characteristic feature of diabase.

How is diabase used as an architectural stone?

When cut and polished, this diabase can serve as an attractive architectural stone. 2) The pyroxene minerals in diabase, as well as the feldspars, will form a weathering rind when exposed to the elements. So, an initially black construction stone can alter to a chalky white, gray, or tan color.