Identification guide · Materials
How to Identify Blue Goldstone
Blue Goldstone is usually dark blue, navy, and sparkly with a vitreous luster and is opaque. It has a Mohs hardness of 5.5. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. Its streak is white to colorless. It is most often confused with Glass, Opalite, and Slag Glass; the tests below separate them.
Blue Goldstone identification checklist
| Color | Dark Blue, Navy, Sparkly, Metallic specks | Look at a clean, dry surface in daylight. Color zoning, banding or spots are as diagnostic as the hue. |
|---|---|---|
| Luster | Vitreous | Fresh surfaces shine like glass; a dull surface usually means weathering, so chip or wet a corner. |
| Transparency | Opaque | Hold a thin edge up to a bright light and note whether light passes through. |
| Mohs hardness | 5.5 | It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will. |
| Streak | White to colorless | Drag a corner across unglazed porcelain (the back of a bathroom tile) and check the powder color. |
| Cleavage | None | |
| Fracture | Conchoidal | Broken surfaces show smooth, curved, shell-like scoops. |
| Specific gravity | 2.5 | Ordinary rock-like heft (specific gravity about 2.5), similar to quartz. |
| Crystal system | Amorphous |
Extra tests for Blue Goldstone
Glass check. Blue Goldstone shares a glassy luster and conchoidal fracture with man-made glass. Glass sits near Mohs 5.5 and often contains round gas bubbles, so a hardness test and a hand lens separate them.
Blue Goldstone look-alikes and how to tell them apart
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Blue Goldstone vs Glass →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Blue Goldstone vs Opalite →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Blue Goldstone vs Slag Glass →
Both sit near Mohs 5.5, so a scratch test alone will not separate them. Lean on luster, streak and heft instead. Blue Goldstone vs Lapis Lazuli →
Field tips
- Look for a uniformly dark blue glassy body with tiny sparkly points.
- Check for glass-like conchoidal chips or bubbles on damaged edges.
- Do not confuse the retail name with natural aventurine or natural feldspar sunstone.
Blue Goldstone identification FAQ
How can you tell if a rock is Blue Goldstone?
Check the color (dark blue, navy, sparkly, and metallic specks), the vitreous luster, a Mohs hardness of 5.5 and a white to colorless streak. Photographing it with the StoneSnap app gives a match in seconds.
What is the hardness of Blue Goldstone?
Blue Goldstone has a Mohs hardness of 5.5. It is about as hard as window glass: a knife barely marks it, while a steel file (Mohs 6.5) will.
What is the difference between Blue Goldstone and Glass?
Blue Goldstone (Mohs 5.5, vitreous luster) and Glass (Mohs 5.5, vitreous luster) look alike, but hardness, streak and heft usually separate them. See the full Blue Goldstone vs Glass comparison for a side-by-side table.
Is Blue Goldstone worth anything?
Entry-level Blue Goldstone specimens sell for around $3, typical collector pieces about $15, and premium examples $80 or more depending on size, quality and locality.
What color is Blue Goldstone?
Blue Goldstone is most often dark blue, navy, sparkly, and metallic specks. Color varies with impurities and locality, so confirm with hardness and luster rather than color alone.
