Sandstone
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Sandstone is a clastic sedimentary rock composed mainly of sand-sized silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks.
Cut slab of sandstone
Alcove in the Navajo Sandstone
Kokh-type tombs cut into the multicoloured sandstone of Petra
Sand grains of quartz with hematite coating providing an orange colour
Feldspar
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Feldspar is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the
Sandstone
…silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar because they are the most resistant minerals to the weathering processes at the Earth's surface. Like uncemented sand, sandstone may be imparted any…
Specimen of rare plumbian (lead-rich) feldspar
Crystallized white feldspar, with an upright 4 cm aquamarine crystal perched on it
Feldspar and moonstone, from Sonora, Mexico
A cluster of euhedral feldspar crystals with a schorl crystal