Raw Stones
303 pieces
Tumbled Stones
202 pieces
Palm Stones
37 pieces
Crystal Points
38 pieces
Clusters & Geodes
61 pieces
Polished & Decor
146 pieces
Mineral Specimens
130 collector pieces
Crystal Chips
22 pieces
Browse everything
Every collection, one page.
View All Collections →
Aries
Mar 21 – Apr 19
Carnelian
›
Taurus
Apr 20 – May 20
Rose Quartz
›
Gemini
May 21 – Jun 20
Agate
›
Cancer
Jun 21 – Jul 22
Moonstone
›
Leo
Jul 23 – Aug 22
Citrine
›
Virgo
Aug 23 – Sep 22
Amazonite
›
Libra
Sep 23 – Oct 22
Blue Lace Agate
›
Scorpio
Oct 23 – Nov 21
Obsidian
›
Sagittarius
Nov 22 – Dec 21
Sodalite
›
Capricorn
Dec 22 – Jan 19
Black Tourmaline
›
Aquarius
Jan 20 – Feb 18
Amethyst
›
Pisces
Feb 19 – Mar 20
Aquamarine
›
Gifting?
A birthday stone is the safe bet.
Read the zodiac guide →
Pentagonite
Pentagonite is phyllosilicate (calcium vanadium, cavansite dimorph), Ca(VO)Si₄O₁₀·4H₂O. In the hand, it rates 3 to 4 on the Mohs scale, and it runs electric sapphire blue and greenish blue. Cavansite's rare twin, same electric blue, but in SPIKY needle stars and four-armed cross twins instead of rounded rosettes.
The geology.
Pentagonite carries the formula Ca(VO)Si₄O₁₀·4H₂O. It belongs to the orthorhombic system. The trade files it under phyllosilicate (calcium vanadium, cavansite dimorph).
It sits at 3 to 4 on the Mohs scale. The surface reads vitreous. Light behaviour is transparent to translucent. Specific gravity runs 2.2 to 2.3. The streak is bluish white. It breaks with good cleavage; brittle.
Cavansite's rare twin, same electric blue, but in SPIKY needle stars and four-armed cross twins instead of rounded rosettes.
Common cuts are spiky four-armed star twins or radiating needle sprays on matrix.
The origins.
Wagholi quarries, Pune, India, found alongside cavansite but far scarcer.
On value, the database notes: prized; genuine star sprays command strong premiums.
Traditional associations.
In energy work traditions, shares cavansite's intuition and clear-speech associations.
Included for completeness. Tradition is worth knowing about, and it is worth keeping separate from the mineralogy.
Spotting the real thing.
Cavansite's rare twin, same electric blue, but in SPIKY needle stars and four-armed cross twins instead of rounded rosettes.
Cavansite sold 'as pentagonite' is the common upsell, stars versus balls settles it.
| Looks like | How to tell them apart |
|---|---|
| Cavansite | Identical chemistry, cavansite makes rounded balls, pentagonite makes sharp stars; the habit IS the identification |
| Azurite | Azurite is navy, heavier, and acid-reactive |
| Dyed druzy | Dye pools at bases and wipes off |
At-home tests.
These checks cost nothing. Daylight, a 10x loupe and a little patience are the whole kit for pentagonite.
| Test | What you should see |
|---|---|
| By eye | Spiky star/cross habit |
| By eye | Featherlight zeolite-style matrix |
| By eye | Even blue with no dye pooling |
Stop short of anything that leaves a mark. A gemologist can answer the rest without damaging the stone.
Care & handling.
At 3 to 4 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with good cleavage; brittle, which is worth knowing before you set it or drop it.
Skip the ultrasonic. Lukewarm water, mild soap and a soft cloth handle routine cleaning without risk.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is Ca(VO)Si₄O₁₀·4H₂O. Crystal system: Orthorhombic. Specific gravity: 2.2 to 2.3. Streak: Bluish white. Cleavage and fracture: Good cleavage; brittle.
How it reaches the market
Wagholi quarries, Pune, India, found alongside cavansite but far scarcer.
What it gets confused with
Cavansite: Identical chemistry, cavansite makes rounded balls, pentagonite makes sharp stars; the habit IS the identification. Azurite: Azurite is navy, heavier, and acid-reactive. Dyed druzy: Dye pools at bases and wipes off.
What it is worth
Prized; genuine star sprays command strong premiums.
Where buyers get caught
Cavansite sold 'as pentagonite' is the common upsell, stars versus balls settles it.
One more thing
Named for its five-fold twin crosses, pentagonite is the showier, rarer sibling that collectors pay multiples for.
An education-first guide.
We do not carry pentagonite. This page exists because the question comes up and the honest answer is worth writing down, whether or not there is anything here to sell you.
Explore the Crystal Guide