[Zer0 (OP)]

Any ordinary looking small rock on the side of the road, what is it made up of?

& the fine grainy sand at a beach, what's inside a single miniscule grain of sand?

(clueless about geology hence donno how to ask the question, plz do not waste ur precious time n try to keep responses short & brief)

[paul cotter]

Sand is mostly silica and feldspar( a complex silicate ). Other rocks are often complex mixes but the vast bulk of rock material is also silica+silicates.

[Halc]

Any ordinary looking small rock on the side of the road, what is it made up of?

A native rock (one not put there by the road construction process) is sometimes just the local stuff, which would be loose slate near me.

what's inside a single miniscule grain of sand?

Sand is usually something from the watershed of nearby rivers. I grew up in Michigan where the entire lower part of the state is made up of sand and rocks, made of, well, Canada actually. None of it is 'native', but instead all pushed there from up north. Somewhere deep down is actual Michigan rock, but none of us has actually seen it.
Go to Florida and all the sand is made entirely of ground-up sea shells. In Hawaii the sand is black volcanic stuff. Local stuff in all cases.

Where I live now the beaches are all fake, so who knows where they found the stuff.

[evan_au]

When I was at high school,we were told that there are two major classes of rock:
- SIAL: Short for Silicon + Aluminum, these lighter rocks (in colour & density) make up the continental crust
- SIMA: Short for Silicon + Magnesium, these darker & denser rocks make up the oceanic crust and lower layers of the continental crust. They also appear in basaltic volcanoes (like Hawaii).
- The lighter SIAL continental crust tends to float over the denser SIMA rocks.

But all rocks are a mix of many different elements, in various concentrations. When rocks solidify from a melted state, different minerals form individual grains with different chemical composition and crystal structure
- When a rock is weathered, the softer/more reactive minerals are broken down first, releasing the grains of harder/less reactive minerals to be moved by water and wind. In many places, these more resistant grains are silica, producing the familiar deserts and beaches made of white/yellow silica sand.

There is a suggestion in Wikipedia that these terms are antiquated (like me), but the two broad categories are still relevant.
https://en.wikipedia.org/wiki/Sial
https://en.wikipedia.org/wiki/Sima_(geology)

[Zer0 (OP)]

Thanks All.
Good responses!

ps - so rocks n sand is Valuable, besides We got soo muchh of it, GR8!

[evan_au]

sand is Valuable, besides We got soo much of it,

Sand is quite valuable, forming a large component of our roads and reinforced concrete buildings.

But not any sand will do:
- There are huge deserts in the world, but apparently wind-blown sand is too "smooth", and does not form a strong bond
- There are huge oceans in the world, but the salt in marine sand causes "concrete cancer"
- So that basically leaves river sand, of which there is a very limited supply. Dredging river sand disrupts ecosystems and is unsightly for the people who live near the rivers.