en.wikipedia.org/wiki/Quartz

This sentence appears to mix up Earth’s crust with the lithosphere.

• The well-known mineral-abundance figures of roughly feldspar ~50%, quartz ~12%, and pyroxene ~11% are standard figures for the Earth’s crust.
• But the lithosphere is not just crust: it includes the crust plus the brittle upper mantle.
• The lithospheric mantle is composed mainly of peridotite, which is dominated by olivine and pyroxene, not quartz.

Because the lithosphere includes a substantial mantle component, a crust-only number like 12% quartz cannot correctly describe the lithosphere as a whole. In other words, the article’s percentage is attached to the wrong Earth layer.

A more accurate phrasing would be that quartz is among the most abundant minerals in the continental crust / Earth’s crust (depending on the source being cited), not in the entire lithosphere.

This sentence assigns a crustal mineral-composition breakdown to the lithosphere, which is a broader layer.

Why it is incorrect:

1. The lithosphere includes the upper mantle as well as the crust.
   National Geographic defines the lithosphere as including both the crust and the brittle upper portion of the mantle.

2. The lithospheric mantle is not feldspar-and-quartz-dominated.
   The upper mantle below the Moho is characterized as peridotite, made mostly of olivine and pyroxene.

3. The quoted 41% / 12% / 11% breakdown is a crust figure.
   The same percentages appear in geology teaching materials as the mineral makeup of the Earth’s crust: about 39% plagioclase feldspar + 12% alkali feldspar (~51% feldspar total), 12% quartz, and 11% pyroxene.

So the problem is not the percentages themselves, but the layer they are being applied to. Those numbers describe the crust, not the entire lithosphere.