Helenite: Gemstone Found in Volcano

Helenite is Amazing Gemstone made from the fused volcanic rock dust from Mount St.

Helenite is a man-made glass made from the fused volcanic rock dust from Mount St. Helens and marketed as a gemstone. Helenite was first created accidentally after the eruption of Mount St. Helens in 1980.

It is sold as facet rough, faceted stones, tumbled stones, and mounted in finished jewelry. The material has been produced in a variety of green, red, and blue hues, which are produced or enhanced by adding coloring agents to the melt. Tourists visiting Mount St. Helens are the primary market for the novelty colored stone jewelry made with helenite.

Helenite was first created accidentally after the eruption of Mount St. Helens in 1980. Workers from the Weyerhaeuser Timber Company were attempting to salvage equipment damaged after the volcanic eruption. Using acetylene torches, they noticed that the intense heat was melting the nearby volcanic ash and rock and turning it a greenish color.

Helenite is a man-made glass made from the fused volcanic rock dust from Mount St. Photo: Ryan Masin

As word of the discovery spread, jewelry companies took note and began to find ways to reproduce the helenite. Helenite is made by heating rock dust and particles from the Mount St. Helens area in a furnace to a temperature of approximately 2,700 °F (1,480 °C). Although helenite and obsidian are both forms of glass, helenite differs from obsidian in that it is man-made.

The gem species of Helenite is categorized as Silicate and on the Moh's scale, it only registers at a 5 for hardness. Although there are variations in this data. Other resources and gem providers list Helenite at a hardness of 6 to 7.5 on the hardness scale.

The stone has been marketed by the jewelry industry because of its emerald-like color, good refractive index, and durability. It is seen as an inexpensive alternative to naturally occurring green gemstones like emerald and peridot. Helenite can also come in various red, green and blue varieties.

Other names for it are Mount St. Helen's Obsidian, Emerald Obsidianite, and Ruby Obsidianite although the most common term used is Helenite. It is important to note however, that although Obsidian is referenced in name variants, Helenite is not an actual Obsidian. Obsidian is characterized by naturally occurring volcanic glass.

Faceted red helenite. Photo: B. Cedric

The ash has a basic composition that is similar to the igneous rock known as dacite. It consists of approximately 65% SiO₂, 18% Al₂O₃, 5% Fe₂O₃, 4% CaO, 4% Na₂O, and 2% MgO. Numerous trace and minor elements also occur in the ash.

Helenite does not come in any other color other than red or green. 

Helenite is not rare.  There are trillions of cubic tons of this volcanic ash and mud available to create this material.  A five gallon bucket full of ash will make many thousands of carets of  this so-called gem.  Anyone with a heat source can create it, and many thousands of pounds of it has been made in back-yard smelters and professionally set up laboratories.