Aegirine

ID	453
Mineral	Aegirine
Location	Mount Malosa - Zomba - Southern Region - Malawi
Fluorescence	LW-UV: close SW-UV: close
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Mindat data

ID	31
Long ID	1:1:31:0
Formula	`NaFe³⁺Si₂O₆`
IMA Status	0 1
Other Occurrences	Common in alkalic igneous rocks, carbonatites, and pegmatites; from regionally metamorphosed schists, gneisses, and iron formations; in blueschist facies rocks, and from sodium metasomatism in granulites; authigenic in some shales and marls.
Discovery Year	1821
Diapheny	Transparent,Opaque
Cleavage	Good on {110}
Tenacity	brittle
Colour	Dark green to greenish black, reddish brown, black
Hardness (min)	6.0
Hardness (max)	6.0
Lustre	Vitreous, resious
About the name	First described as acmit by P. H. Ström (1821) from Rundemyr, Øvre Eiker, Buskerud, Norway for a mineral earlier mentioned shortly by Strøm (1784, as "crystalliseret hornsteen eller brun kantet og riflet Schoel i quarz" (crystallized hornstone or brownish angular and grooved schorl in quartz)). Ström (1821) recognized it as a new mineral and suggested the name wernerin, after the german geologist, Abraham Gottlob Werner. But Berzelius (1821), who analyzed the mineral, named it achmit after the greek αχμη, spear point, due to the habit of the crystals. Later, in 1834, the priest and mineralogist Hans Morten Thrane Esmark found a new mineral on Låven, Langesundsfjorden, Norway which was described and given the name aegirine, after Ægir (Aegir), the sea god in Norse mythology because the type location was along the sea shore (Berzelius 1835). Acmite and aegirine were first believed to be two separate species, one belonging to the amphiboles (acmite) and the other to the pyroxenes (aegirine). This was the case until 1871 when G. Tschermak put forward evidence that acmite and aegirine both belonged to the pyroxenes and are the same mineral. Acmite has been considered as a variety of aegirine (historically acmite had priority, so it should have been the other way around).
Streak	Pale yellowish grey
Crystal System	Monoclinic
Cleavage Type	Distinct/Good
Fracture type	Irregular/Uneven
Morphology	Prismatic crystals, showing 110, with blunt to steep terminations, to 35 cm, striated lengthwise, can be bent or twisted. In sprays of acicular crystals, fibrous, in radial concretions.
Twinning	Simple and lamellar on {100}
UV	Not fluorescent in UV
Comment Luster	Slightly resinous
Publication Year	1821
shortcode_ima	Aeg
Group	Clinopyroxene Subgroup

Price: € 20

Dimensions: Not registered

Weight: Not registered

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Notes:

Symbol	Element
Fe	Iron
Na	Sodium
O	Oxygen
Si	Silicium

Aegirine

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