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- A
detrital sedimentary rock formed by
cementation of individual grains of
sand size and predominantly composed of
quartz and
feldspar.
Derived from disintegration of
granite.
Source: Leet, L. Don. 1982.
Physical Geology, 6th Edition. Englewood Cliffs, NJ: Prentice-Hall
- A feldspar-rich sandstone, typically coarse-grained and pink or reddish,
that is composed of angular to subangular grains that may be either poorly
or moderately well sorted; usually derived from the rapid disintegration
of granite or granitic rocks, and often closely resembles granite; e.g.,
the Triassic arkoses of the Eastern United States. Quartz is usually the
dominant mineral, with feldspar (chiefly microcline) constituting at least
25%. Cement (silica or calcite) is commonly rare, and matrix material
(usually less than 15%) includes clay minerals (esp. kaolinite), mica, and
iron oxide; fine-grained rock fragments are often present. Arkose is
commonly a current-deposited sandstone of continental origin, occurring as
a thick, wedge-shaped mass of limited geographic extent (as in a fault
trough or a rapidly subsiding basin); it may be strongly cross-bedded and
associated with coarse granite-bearing conglomerate, and it may denote an
environment of high relief and vigorous erosion of strongly uplifted
granitic rocks in which the feldspar was not subjected to prolonged
weathering or transport before burial. Arkose may also occur at the base
of a sedimentary series as a thin blanketlike residuum derived from and
resting on granitic rock. Etymol: French, probably from Greek archaios,
ancient, primitive. Syn: arkosic subarkose. Also spelled arcose. AGI
Source:
Dictionary of Mining, Mineral, and Related Terms
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