feld·​spar ˈfel(d)-ˌspär How to pronounce feldspar (audio)
: any of a group of crystalline minerals that consist of aluminum silicates with either potassium, sodium, calcium, or barium and that are an essential constituent of nearly all crystalline rocks

Examples of feldspar in a Sentence

Recent Examples on the Web With their distinctive bands and sporadic veins of quartz and feldspar, the stones sparkle whenever sunlight strikes them. Dan Falk, Discover Magazine, 6 Apr. 2024 In the lab, the researchers then peered inside individual sand grain crystals of quartz and feldspar to measure environmental radiation that accumulated over thousands of years in the dune’s dark depths. Mindy Weisberger, CNN, 4 Mar. 2024 That technique reveals how much time has elapsed since minerals such as quartz and feldspar in the sediments were last buried, Lai said. Katherine Kornei, Discover Magazine, 14 Nov. 2023 The researchers made another trip to the falls, in 2019, and Dr. Duller had planned to use an even more powerful dating technique based on feldspar grains rather than quartz. Carl Zimmer, New York Times, 21 Sep. 2023 What Forni and others see at Campi Flegrei is exactly that: The lava erupted from Monte Nuovo has the signature of one produced from magma that is rapidly crystallizing feldspar. Erik Klemetti, Discover Magazine, 14 Nov. 2018 But what intrigued the researchers was that biotite and feldspar don’t occur together. Roger Lewin, Discover Magazine, 11 Nov. 2019 So instead, Rittenour used light—specifically the luminescence of bits of feldspar buried in the sediment. Matt Simon, WIRED, 20 July 2023 Luminescence dating determines how much time has passed since minerals in the sediment, such as quartz or feldspar, were last heated or exposed to light, according to CNN’s Katie Hunt. Will Sullivan, Smithsonian Magazine, 14 June 2023

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'feldspar.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


modification of obsolete German Feldspath (now Feldspat), from German Feld field + obsolete German Spath (now Spat) spar

First Known Use

1772, in the meaning defined above

Time Traveler
The first known use of feldspar was in 1772

Dictionary Entries Near feldspar

Cite this Entry

“Feldspar.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/feldspar. Accessed 22 May. 2024.

Kids Definition


feld·​spar ˈfel(d)-ˌspär How to pronounce feldspar (audio)
: any of a group of crystalline minerals that consist of silicates of aluminum with potassium, sodium, calcium, or barium and that are a basic part of nearly all crystalline rocks

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