The Hawaiian Islands formed over a stationary hot spot, continually feeding magma from the Earth’s mantle to the surface. This volcanic origin means the islands possess a distinct suite of “gemstones” that differ significantly from those found in continental landmasses. These treasures include crystalline minerals, materials formed rapidly by volcanic activity, and those derived organically from the deep ocean environment. This combination establishes Hawaii’s unique role in the world of natural gems.
The Signature Hawaiian Gem: Peridot (Olivine)
The most recognized crystalline mineral associated with the islands is peridot, the gem-quality form of olivine. Olivine is a magnesium iron silicate, one of the first minerals to crystallize at high temperatures deep within the Earth’s upper mantle. Volcanic eruptions transport these green crystals to the surface, where they become a common component of the dark basaltic rock that makes up the islands.
The mineral is often referred to locally as the “Hawaiian diamond” and is connected culturally to Pele, the goddess of volcanoes. Papakōlea Beach on the Big Island is one of the world’s few green sand beaches and a famous example of olivine concentration. Its distinctive hue is due to the erosion of an ancient cinder cone, which weathered away less dense components, leaving behind a concentration of the heavier, lime-green olivine crystals. Although most of the material is sand-grain sized, transparent pieces of olivine can be cut into the gemstone peridot.
Organic Treasures of the Sea
In contrast to volcanic minerals, Hawaii is known for valuable organic treasures derived from its deep marine environment. The most prominent is black coral, designated as the official state gem of Hawaiʻi in 1987. Unlike shallow-water reef-building corals, black coral thrives in the dark, cold waters of the deep sea, often found between 100 and 1,600 feet below the surface.
Black coral is not a rock or mineral, but the skeletal remains of a marine organism. A colony of tiny polyps secretes this hard, dark-colored proteinaceous skeleton. This material is prized for its ebony luster and is harvested under strict regulation due to its incredibly slow growth rate, with some species growing about 2.5 inches per year.
Other precious corals found in Hawaiian waters include pink coral, which ranges from light whitish tones to deep rose shades, and gold coral, which is uniquely found in Hawaii and Alaska. Hawaiian jewelry also often incorporates black pearls, which are primarily sourced from the black-lip oyster in French Polynesia but have become culturally significant.
Unique Volcanic Glass Formations
Hawaiian eruptions create unique amorphous, or non-crystalline, materials known collectively as volcanic glass. Two delicate and culturally significant formations are named after the volcano goddess: “Pele’s Hair” and “Pele’s Tears.” Pele’s Hair consists of fine, golden-brown strands of volcanic glass, formed when a droplet of molten lava is stretched thin by the wind during a vigorous eruption.
These hair-like filaments are extremely lightweight and can be carried kilometers away from their source vent. Pele’s Tears are small, solidified droplets of jet-black volcanic glass, geologically classified as obsidian, that form when airborne particles rapidly cool. These teardrop-shaped pieces are often found attached to the ends of Pele’s Hair strands. The velocity of the erupting magma is a key factor, with high-velocity eruptions favoring the formation of the fine hair and lower-velocity ejections favoring the tear-shaped droplets.
Legal Considerations and Ethical Collecting
Visitors must be aware of strict legal and cultural restrictions regarding collecting these natural formations. It is illegal under federal and state law to remove any rocks, sand, coral, or other natural resources, including Pele’s Hair and Tears, from National Parks like Hawaiʻi Volcanoes National Park. State law also prohibits the removal of sand and lava rocks from public beaches to prevent coastal erosion and preserve the islands’ unique geology.
The commercial harvesting of deep-sea corals is heavily regulated, requiring special permits and adherence to strict quotas to ensure the sustainability of these slow-growing organisms. Beyond the legal framework, a strong cultural custom emphasizes respect for the land, suggesting that natural items should be left in place. This practice honors the Hawaiian belief that removing these materials disrupts the natural balance and is disrespectful to the land and its deities.