Here, a small grain of copper is impacted into a larger nugget, also of copper. These grains precipitated downwind of an unregulated, smoke-belching copper smelter. (Magnification 110x)

Bright green olivine is a significant mineral in Hawaii’s slow-flowing basaltic lava and is rich in iron. Its density allows it to separate from other sand grains in the rolling and depositing action of waves, which results in the accumulation that tints this beach a yellowish green.(Magnification 110x)

The pitted and frosted surface of these grains is typical of desert sand, where grains constantly collide with one another.(Magnification 85x)

Metamorphic minerals, which form at high temperatures and pressures underground, can become heavy, brightly colored sands like these.(Magnification 95x)

This sand, red from iron oxide, was found at Makena Point, Maui. It eroded from igneous rock, which was produced by the solidification of molten magma. (Magnification 125x)

Not all sand is made of tiny bits of rock. Biogenic sand, which forms from the remains of marine life, is the major ingredient of many tropical beaches. The grains here are tiny fragments of a baby sea urchin shell. (Magnification 100x)

Looking like a puffy white star studded with little pearls, this is the shell of an amoeboid protist called a foraminifera, or foram. The shells, called tests, are made mainly of calcium carbonate, which the animals derive from carbon atoms in the air and water. (Magnification 75x)

The glasslike needles are sponge spicules, which form the internal skeletons of sponges. They are made of silica, can be found in a variety of bizarre shapes. They surround the tip of a spiral shell, composed primarily of calcium carbonate, that has broken off and eroded. (Magnification 70x)

Worms have burrowed trails into this shell fragment. Worms like these are abundant in the ocean as well as on land. (Magnification 110x)

Man-made objects can also become sand. This grain was found on the Greek island of Delos, Greece. Delos had no indigenous marble, and an enormous amount of marble had to be quarried and brought to the island to erect the temples. Over the years, the marble blocks have eroded and the local beaches are now peppered with different types of marble. (Magnification 130x)

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