Apophyllite

Apophyllite is a water-bearing silicate mineral of potassium and calcium. Its crystals are often box-shaped or sharp-tipped prisms, colourless, white, green or pinkish, with a glassy shine and a pearly sheen on their flat top faces. It is found in the same cavities as zeolite minerals and is often mistaken for a zeolite, but it is not one. Being soft, it is more a collector’s stone than a jewellery stone.

Collecting: because of its large, well-formed crystals and variety of colours, it is popular with mineral collectors; crystal clusters are put on display. Ornaments: crystal clusters are used for decoration. Jewellery: being soft (4.5–5) and splitting easily in one direction, it is not much used in jewellery; cut stones are mostly made for collectors.

It has a hardness of 4.5–5 on the Mohs scale. A fingernail cannot scratch it, but a steel knife can. Its specific gravity is 2.33–2.37 g/cm³.

Its best-known localities: Pune (Poona) area, Maharashtra, India; Nashik (Nasik) area, Maharashtra, India; Sankt Andreasberg, Harz Mountains, Germany; Djúpivogur area (Teigarhorn), Berufjörður, Iceland; Bento Gonçalves area, Rio Grande do Sul, Brazil.

Crystals are often box-like (pseudo-cubic) or prisms ending in a sharp pyramid; the prism faces are deeply striated. It has a glassy shine, with a pearly sheen on faces parallel to the base. It may be colourless, white, pale green, pale yellow or pinkish, and is transparent or translucent. It is soft (Mohs 4.5–5): a steel knife scratches it, while glass is not scratched. It splits easily into flat sheets in one direction. Quartz crystals can look like apophyllite, but quartz is much harder (7), scratches glass, and lacks the pearly flat faces at the crystal tips.

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. Clarity and lustre, and the size and shape of the crystals, matter most for apophyllite: undamaged, sharp-tipped and transparent crystals are the most sought after. Colour counts too, and green apophyllite from India is especially popular. A pleasing contrast with the zeolite or calcite beneath the crystals, a well-balanced cluster and unbroken tips add value. Because it is soft and splits easily, it is rarely used as a cut stone; its value comes mostly from being a collector’s specimen.

Today crystal-therapy sellers and websites say that apophyllite is a “stone of truth” that opens the crown and third-eye chakras, strengthens intuition and deepens meditation. The same sources say the stone soothes anxiety and stress, clears “negative energy” and amplifies the effects of other crystals around it. Apophyllite is a water-bearing calcium-potassium silicate; its clear, bright look comes from light reflecting off the crystal faces. There is no scientific evidence that the stone sharpens intuition, opens a chakra, soothes anxiety or boosts other crystals around it. Lasting anxiety or stress calls for a doctor. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.