Well-cleaved, dark, fine-grained chlorite-actinolite metadiabase intrudes light granitic gneiss

Actinolite is an inosilicate mineral with the chemical formula
Ca₂(MgFe)₅Si₈O₂₂(OH)₂ Download high resolution version (550x842, 110 KB)Actinolite Well-cleaved, dark, fine-grained chlorite-actinolite metadiabase (Ymd) intrudes light granitic gneiss along Catoctin Creek, eastern Blue Ridge, Loudoun Co. ... Download high resolution version (550x842, 110 KB)Actinolite Well-cleaved, dark, fine-grained chlorite-actinolite metadiabase (Ymd) intrudes light granitic gneiss along Catoctin Creek, eastern Blue Ridge, Loudoun Co. ... Banded gneiss with dike of granite orthogneiss Gneiss is a common and widely distributed type of rock formed by high grade regional metamorphic processes from preexisting formations that were originally either igneous or sedimentary rocks. ... The silicate minerals make up the the largest and most important class of rock-forming minerals. ... This article is about minerals in the geologic sense; for nutrient minerals see dietary mineral; for the band see Mineral (band). ...

Mineralogy

Actinolite is an intermediate member in a series between tremolite (Mg-rich) and ferro-actinolite (Fe-rich). As seen from the chemical formula above, Mg and Fe ions can be freely exchanged in the crystal structure. Amphibole (Hornblende) Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. ...

Occurrence

Actinolite is commonly found in metamorphic rocks, such as contact aureoles surrounding cooled intrusive igneous rocks. It also occurs as a product of metamorphism of magnesium-rich limestones. Metamorphic rock is the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means change in form (from the Greek words meta, change, and morphe, form). The protolith is subjected to extreme heat (greater than 150 degrees Celsius) and pressure causing... Pluton redirects here. ... Volcanic rock on North America Plutonic rock on North America Igneous rocks are formed when molten rock (magma) cools and solidifies, with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks. ... Metamorphism can be defined as the mineralogical, chemical and crystallographic changes in a solid-state rock, i. ... Limey shale overlaid by limestone. ...

Some forms of asbestos are formed from fibrous actinolite, the fibres being so small that they can enter the lungs and damage the alveoli. Another form of actinolite, known as nephrite, is one of the two common constituents of jade (the other being jadeite). Asbestos (Greek ἄσβεστος: a-, not; sbestos, extinguishable) describes any of a group of fibrous metamorphic minerals of the hydrous magnesium silicate variety. ... The alveoli (singular:alveolus), tiny hollow sacs which are continuous with the airways, are the sites of gas exchange with the blood. ... A selection of antique, hand-crafted Chinese jadeite jade buttons Jade An ornamental stone, jade is a name applied to two different silicate minerals. ... Jadeite is a pyroxene mineral with composition NaAlSi2O6. ...

Details

Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer. ... The refractive index of a material is the factor by which the phase velocity of electromagnetic radiation is slowed relative to vacuum. ... Pleochroism is an optical phenomenon where due to double refraction of light by a colored gem or crystal, the light is divided into two paths which are polarized at a 90° angle to each other. ...

Related minerals

1. Tremolite
2. Jade

Amphibole (Hornblende) Amphibole defines an important group of dark-colored rock-forming inosilicate minerals composed of double chain SiO4 tetrahedra linked at the vertices and generally containing ions of iron and/ or magnesium in their structures. ... A selection of antique, hand-crafted Chinese jadeite jade buttons Jade An ornamental stone, jade is a name applied to two different silicate minerals. ...

Reference

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0471805807

External links

• Mindat.org
• Webmineral.org