greisen

[grahy-zuhn]

noun

1. a hydrothermally altered rock of granitic texture composed chiefly of quartz and mica, common in the tin mines of Europe.

greisen

/ ˈɡraɪzən /

noun

1. a light-coloured metamorphic rock consisting mainly of quartz, white mica, and topaz formed by the pneumatolysis of granite

Word History and Origins

Origin of greisen¹

Borrowed into English from German around 1875–80

Word History and Origins

Origin of greisen¹

C19: from German, from greissen to split

Example Sentences

The analyses show the composition of Cornish granite and greisen.

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Cassiterite usually occurs as veins or impregnations in granitic rocks, and is especially associated with the quartz-mica rock called greisen.

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The wall rocks are usually strongly altered and in part are replaced by some of the above minerals, forming coarse-grained rocks which are called "greisen."

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The latter is a pneumatolytic product consisting of quartz and tourmaline; it often contains white mica and thus passes by all stages into greisen.

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They make it clear that there has been an introduction of fluorine and boron and a diminution in the alkalies during the transformation of the granitic rock into the greisen.

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