Aventurine is a quartz rock, usually a fine-grained quartzite, that contains small flat mineral flakes. When light hits the flakes, they glint like glitter, an effect called aventurescence. Green aventurine, colored by a chromium mica called fuchsite, is the most familiar kind. Blue, red, orange, brown and yellow aventurine also exist, each colored by a different mineral.
What aventurine is
Most aventurine is quartzite: a rock made of many interlocking quartz grains. A smaller share is massive quartz. In both cases, the sparkle comes from platy inclusions spread through the quartz. The flakes are all at slightly different angles, so as you move the stone, different flakes catch the light.
Because it is a rock, aventurine varies from piece to piece. Some material has a dense, even color with fine sparkle. Other pieces look pale or patchy, with only a few bright flakes. Quartzite forms when sandstone is heated and compressed, one of the processes covered on our page about metamorphic rocks and gemstones.
The name has an unusual origin. It comes from the Italian a ventura, "by chance," a reference to a glass made in Venice. According to a long-repeated story, glassmakers on Murano produced a sparkling glass by accident when copper filings fell into a batch. That glass, now called goldstone, was named "aventurine glass," and the natural stone later took the name from it.
How aventurescence works
Aventurescence is a reflection effect. Each mineral flake acts like a tiny mirror inside a transparent to translucent host. You see a spangled glitter instead of a moving band of light (chatoyancy) or a soft sheen (adularescence). The page on gemstone optics compares these phenomena side by side.
The same effect appears in feldspar. Feldspar with copper or hematite platelets is sold as sunstone, and older books sometimes call it "aventurine feldspar." In modern usage, plain "aventurine" means the quartz material.
Colors of aventurine
Green aventurine
Green aventurine owes its color to fuchsite, a chromium-bearing variety of muscovite mica. The color ranges from pale mint to deep forest green. India has long been a large source, and Brazil, Russia and other countries also produce it. Because of the chromium, green aventurine often looks reddish or pinkish through a Chelsea color filter, a quick test described on our page about gemological instruments.
Green aventurine has been sold under the trade name "Indian jade." It is unrelated to true jade, which is jadeite or nephrite. Aventurine has a lower specific gravity and refractive index, and its sparkle gives it away under a loupe.
Blue aventurine
Blue aventurine is less common. The color usually comes from inclusions of blue minerals such as dumortierite. Blue quartzite colored by dumortierite is sometimes sold simply as dumortierite.
Red, orange and brown aventurine
Hematite or goethite flakes give aventurine a red, orange or brown color with a coppery shimmer. These stones can look very similar to goldstone glass at first glance.
Yellow and other colors
Yellow, peach, white and gray aventurine are also sold. Their colors come from different mixes of mica, iron minerals and other inclusions. Very bright or unusual shades may be dyed, so ask about treatment.
Aventurine and goldstone glass
Goldstone is a man-made glass full of tiny copper crystals. It comes in reddish brown, and a dark blue version is also common. Goldstone is often sold as "sandstone," "monk's gold" or even "aventurine," which creates real confusion. Our page on glass in jewelry covers goldstone with other glass imitations.
You can usually tell the two apart with a 10x loupe:
- Goldstone sparkles from sharp triangular or hexagonal copper crystals of very even size, spread evenly through the glass.
- Natural aventurine has irregular flakes of mixed size, unevenly spread, often with visible quartz grains.
- Goldstone may contain round gas bubbles, which never occur in natural aventurine.
- Goldstone's sparkle is usually much denser and more uniform than that of natural stone.
Treatments and imitations
Most aventurine is untreated. Some pale or grayish quartzite is dyed green to imitate fine green aventurine or jade. Dyed material may show color concentrated in cracks and between grains. Since dye can fade or wear, it should be disclosed. The gemstone treatments page explains how dye is detected.
Green glass and plastic are also used as imitations. Glass usually lacks real platelets and may show bubbles or swirl marks.
Uses of aventurine
Aventurine is opaque to translucent, so it is cut as cabochons, beads and carvings instead of faceted stones. It is common in bead necklaces and bracelets, tumbled stones, small sculptures, bowls and inlay.
Aventurine is generally inexpensive. Even color, strong sparkle and a good polish raise its appeal. Fine, translucent green material with dense, bright flakes is the most desirable.
Durability and care
As a quartz material, aventurine is about 6.5 to 7 on the Mohs scale and has no cleavage. It stands up well to daily wear in rings and bracelets. Very mica-rich pieces can be slightly softer and may take a less even polish.
Clean aventurine with warm soapy water and a soft brush. Untreated aventurine is stable in light and in normal temperatures. Dyed stones should be kept away from solvents and long sun exposure. For other quartz gems with eye-visible inclusions, see rutilated quartz.
Frequently asked questions
What makes aventurine sparkle?
Small flat mineral flakes inside the quartz reflect light like tiny mirrors. In green aventurine the flakes are fuchsite mica, and in red or orange aventurine they are usually hematite or goethite.
Is goldstone the same as aventurine?
No. Goldstone is glass containing copper crystals, while aventurine is a natural quartz rock. Goldstone's sparkle is more even and its crystals have sharp geometric shapes.
Is green aventurine a kind of jade?
No. Green aventurine has been sold as "Indian jade," but it is quartzite. True jade is jadeite or nephrite, which are different minerals.
Can aventurine be worn every day?
Yes. Aventurine is about 7 on the Mohs scale and has no cleavage, so it suits rings, bracelets and other everyday jewelry.