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Minette (a type of lamprophyre), from Jáchymov in the Czech Republic. Lamprophyres (from Ancient Greek λαμπρός (lamprós) 'bright' and φύρω (phúrō) 'to mix') are uncommon, small-volume ultrapotassic igneous rocks primarily occurring as dikes, lopoliths, laccoliths, stocks, and small intrusions.
A dike of lamprophyre near the Shiprock volcanic plug, New Mexico, that has resisted the erosion that removed some of the softer rock into which the dike was originally intruded. A magmatic dike is a sheet of igneous rock that cuts across older rock beds.
Lamprophyre from the Piégut-Pluviers Granodiorite. Lamprophyre dikes are fairly common in the metamorphic country rocks of the granodiorite, but extremely rare in the massif itself. Unweathered lamprophyres have a dark green to green colour; they are very dense fine-grained rocks that weather in creamy colours.
The sapphire bearing Yogo dike is a dark gray to green intrusive rock known as a lamprophyre. The lamprophyre is an unusual igneous rock that contains a low content of silica . The rock has a porphyritic texture with large crystals of orthopyroxene and phlogopite set in a fine grained matrix .
A dike composed of the ultrapotassic igneous rock, lamprophyre Ultrapotassic igneous rocks are a class of rare, volumetrically minor, generally ultramafic or mafic silica-depleted igneous rocks . While there are debates on the exact classifications of ultrapotassic rocks, they are defined by using the chemical screens K 2 O/Na 2 O > 3 in much ...
Sample of lamproite [1]. Lamproite is an ultrapotassic mantle-derived volcanic or subvolcanic rock.It has low CaO, Al 2 O 3, Na 2 O, high K 2 O/Al 2 O 3, a relatively high MgO content and extreme enrichment in incompatible elements.
Dacite usually forms as an intrusive rock such as a dike or sill. Examples of this type of dacite outcrop are found in northwestern Montana and northeastern Bulgaria. Nevertheless, because of the moderately high silica content, dacitic magma is quite viscous [9] and therefore prone to explosive eruption.
Trondhjemite is a leucocratic (light-colored) intrusive igneous rock.It is a variety of tonalite in which the plagioclase is mostly in the form of oligoclase. [1] Trondhjemites that occur in the oceanic crust or in ophiolites are usually called plagiogranites.