Sand under microscope

Sand at 60X

Same image 3X'ed in the editor.

Not mine below.  Waianapanapa, Maui Sand   Much larger.

After some debate it is not volcanic.   Would need to be more solid and this is much too fine.  A better guess is fine shale.   Shale on its way back to clay.

But I emailed the images to a Mineralogist at The University of Oklahoma and he stated "Difficult to tell from these photos, but yes it looks like volcanic sand, not river sand. Besides
being dark in color, it is very angular. It has not been transported by water."

The following maybe wishful thinking or it may apply.  As things generally go I aspect it does not.  On the off chance this stuff is refractory it needs exploring.

I dug around the internet and found
Series: National Park Service Geodiversity Atlas NPS Geodiversity Atlas—Capulin Volcano National Monument, New Mexico

The pertinent paragraph follows.

"Capulin Basalt. Capulin Volcano National Monument and the surrounding area are composed entirely of a single, formally named map unit— Capulin Basalt. Analysis of rock samples from Capulin Volcano and nearby Baby Capulin, a cinder cone outside the monument, found that the rock is technically a “trachybasalt,” having more abundant alkali elements, such as sodium and potassium, than true basalt. The presence of Dakota Sandstone xenoliths (foreign rock fragments) and xenocrysts (foreign crystals) is a characteristic feature of Capulin Basalt. Silica from Dakota Sandstone quartz grains is a factor in the relatively high amount of silica (50%–55%) in Capulin Basalt."

and from various places on  Wikipedia
Jump to search

Trachybasalt is a volcanic rock with a composition between trachyte and basalt. Minerals in trachybasalt include alkali feldspar, calcic plagioclase, olivine, clinopyroxene and likely very small amounts of leucite or analcime.^[1] Trachybasalt is a basalt with high alkali content (5 to 7% Na₂O + K₂O, see TAS diagram).

"Feldspar is a common raw material used in glassmaking, ceramics, and to some extent as a filler and extender in paint, plastics, and rubber. In glassmaking, alumina from feldspar improves product hardness, durability, and resistance to chemical corrosion: …. Chemical weathering of feldspars results in the formation of clay minerals^[16] such as illite and kaolinite.

Kaolinite has a low shrink–swell capacity and a low cation-exchange capacity (1–15 meq/100 g). It is a soft, earthy, usually white, mineral (dioctahedral phyllosilicate clay), produced by the chemical weathering of aluminium silicate minerals like feldspar. In many parts of the world it is colored pink-orange-red by iron oxide, giving it a distinct rust hue.