While the most common image of beaches includes white sand and palm trees, beaches come in a rainbow of colors, from (almost) pure white to midnight black. That's because sand itself is the product of erosion, mainly of inland rocks or sea cliffs. As these rocks or cliffs weather over time—due to rain, wind, snow and other forces—particles are broken off and deposited on beaches via rivers or wind. Sand can also come from marine organisms, creatures whose shells or other hard parts are broken down by the ocean and deposited on the shore. Most light-colored beaches are made of quartz, but depending on what the rocks or cliffs surrounding a beach are made of, a beach can take on an entirely different hue.
Glass Beach—Kauai, Hawaii
It's not the sand that makes this Hawaiian beach so unique—it's the sea glass. On the southern shore of Kauai, near an industrial area, lays Glass Beach, whose shore is covered with a prismatic assortment of sea glass. The sea glass on Hawaii's beaches is distinct from sea glass elsewhere, especially compared to the eastern coast of the United States, because Hawaii's sea glass is often more round in shape (thanks in part to Hawaii's large waves) and contains more shades of blue than usually found elsewhere. Kauai's glass beach might be beautiful, but it owes its existence to a industrial garbage dump nearby—still, it takes the ocean decades (sometimes as long as 30 years) to transform broken bottles and other bits of trash into beautiful, smooth sea glass.
Papakolea Green Sand Beach—Hawaii, Hawaii
The Big Island isn't necessarily known for its white sand beaches—as the youngest island of the Hawaiian archipelago, Hawaii's beaches are much more rugged, shaped even to this day by an active volcano. But along Hawaii's shorelines, there are a few incredible gems, including Papakolea Beach, known for its green sand. The beach's sand gets its beautiful green color from the mineral olivine, which was deposited on its shores years ago by a now-dormant volcano. Magma from volcanoes is rich in olivine, and it's often one of the first crystals to form as lava cools—because of this, olivine is sometimes referred to as "Hawaiian Diamond." Olivine crystals are especially dense, which helps them accumulate on the beach without being washed away by the Hawaiian tides.
Pink Sands Beach—Harbour Island, The Bahamas
This beach on Harbour Island in the Bahamas is like something out of a Barbie dream world–almost three miles of a baby-pink sand beach. The beach gets its rose-colored hue from foraminifera, single-celled marine organisms whose red shells mix with the beach's white sand, creating its distinct pink color.
Punalu'u Beach–Hawaii, Hawaii
Hawaii's Punalu'u Beach almost looks like a film negative of a traditional beach, thanks to its jet-black sand. The sand is composed of basalt, a common igneous rock formed when lava rapidly cools. In the case of Punalu'u Beach, underwater volcanic vents ooze magma, which rapidly cools and explodes when it comes into contact with the much cooler ocean water, creating the shards of basalt that line the beach.
Hyams Beach—New South Wales, Australia
There are a lot of white sand beaches in the world, but only one is listed in the Guinness Book of World Records as having the whitest beach of all: Hyams Beach in New South Wales, Australia. Composed of extremely fine quartz particles, the sand at Hyams Beach is so white that many who have visited note that it's almost necessary to wear sunglasses to protect your eyes from sun reflecting off the sand.
Red Sand Beach—Prince Edward Island, Canada
Prince Edward Island's striking red beaches are due to the iron-rich sand that lines the island's shores; when iron comes into contact with oxygen, it forms iron oxide—better known as rust. Red soil can be found across the entire island, and is so prevelant because the island is formed from soft, sedimentary red sandstone.
Pfeiffer Beach—Big Sur, California
Located along a remote stretch of California's Big Sur, Pfeiffer Beach stuns visitors with its deep violet sand. The color comes from manganese garnet in the surrounding hills, which has been eroded and washed downstream to the beach. Pfeiffer Beach isn't entirely purple sand—the concentration of purple varies throughout the beach, and most of the purple sand can be found on the northern part of the shore. Time of year matters as well—visitors are more likely to see high concentrations of purple sand after winter storms, which help speed erosion of the manganese garnet.
Shelter Cove—Humboldt County, California
The grey sand at Shelter Cove in California's Humboldt County isn't a product of black sand mixing with white sand. Instead, the grey-hued sand is a result of centuries of erosion from nearby shale cliffs.