silicates
Apophyllite
- Also known as
- fluorapophyllitefish-eye stone
- Crystal system
- tetragonal
- Hardness
- 4.5–5 on the Mohs scale
- Lustre
- vitreous
- Colour
- Colourless, white, green, pink
- Where it forms
- In cavities in basalt, alongside zeolites, deposited by low-temperature fluids. The Deccan Traps of western India are the classic source.
- Chiefly from
- Maharashtra, IndiaBrazilIcelandNew Jersey, United States
Why it is that colour
Usually colourless; the green variety is coloured by vanadium.
Safety
Safe to handle. It cleaves perfectly in one direction and is soft, so specimens are easily damaged.
Where it comes from
Overwhelmingly from quarries in the Deccan Traps near Pune and Nashik, where the minerals are a by-product of basalt quarried for road stone. Indian specimen supply is therefore tied to construction rather than to mineral demand.
Historical use
Of little economic use. It is collected for the quality of its crystals.
Recorded as history and attributed where possible. That a stone was used for something establishes that people used it, not that it worked.
What is attributed to it, and since when
Named in 1806 from the Greek for it flakes off, because it exfoliates when heated. No traditional attribution.
Described, not endorsed. Dating a claim is not the same as assessing it — but an association that first appears in a book published in 1985 is not an ancient inheritance, whatever the label says. A sincere account of feeling better is compatible with the stone doing nothing — see the placebo effect.
Worth knowing
Apophyllite is a group rather than a species — the IMA split it in 1978 and again in 2013 into fluorapophyllite, hydroxyapophyllite and natroapophyllite, distinguished by which anion and cation dominate. Almost everything sold as apophyllite is fluorapophyllite-(K).
The Indian trade is worth understanding. These crystals come out of basalt quarried for aggregate, so the supply of some of the world's finest zeolite and apophyllite specimens depends on how much road building is happening in Maharashtra. Quarry workers collect and sell them on the side, which is a rare case of a specimen trade that is genuinely a by-product of something else.
Identity checked against IMA-CNMNC master list, June 2025.