Smithsonite

Smithsonite is a carbonate mineral made of zinc and carbon (ZnCO₃). It mostly occurs not as crystals but as grape-like or kidney-shaped masses, and its colour ranges from white through blue-green to pink and yellow. It is important as an ore of zinc, and attractively coloured pieces are cut as ornamental stones. It is named after James Smithson, the English scientist who first identified it.

Zinc ore: Today it is a minor ore of zinc; in the past it was far more important. Heated together with copper, it was used to make brass. Ornamental stone: Well-coloured, translucent pieces are cut as cabochons and faceted stones. Because it is soft, it needs care in jewellery. Collecting: Coloured masses and large crystals attract mineral collectors.

It has a hardness of 4–4.5 on the Mohs scale. A fingernail cannot scratch it, but a steel knife can. Its specific gravity is 4.3–4.5 g/cm³.

Its best-known localities: Tsumeb, Oshikoto, Namibia; Kelly mine, Magdalena, New Mexico, USA; Lavrio (Laurium), Attica, Greece; Tarnowskie Góry (Tarnowitz), Silesia, Poland; Kabwe (Broken Hill), Central Province, Zambia.

Known localities in Türkiye: Aladağlar (Yahyalı area), Kayseri, Türkiye.

It fizzes when a drop of cold, dilute hydrochloric acid is applied; the very similar hemimorphite does not. Its hardness is 4–4.5: a steel knife scratches it. Its specific gravity is high (about 4.4); it feels distinctly heavier than hemimorphite of the same size (about 3.5). It mostly forms grape-like (botryoidal) or kidney-shaped masses, crusts and stalactites; well-formed crystals are rare. Hemimorphite: it looks very much like smithsonite and occurs in the same deposits; for centuries both were called “calamine”. It is told apart by not fizzing in acid and by being lighter.

On the “street to diamond” value ladder it sits on step 5 of nine: Ornamental stone. As an ornamental stone its value depends on the vividness of the colour (blue-green, pink and green tones), translucency and the evenness and polish of the surface. Crystals are sought after by collectors when they are large, well formed and undamaged, or come from famous places such as Tsumeb or Kelly. Because the stone is soft and cleaves easily, it is rarely used as a faceted gem; the quality of cutting and workmanship matters. As a zinc ore it is a minor ore today; its value depends on its grade and on mining conditions.

Crystal-therapy practitioners claim that smithsonite is soothing and calming, reduces stress and tension, and makes it easier to feel compassion for oneself and others. The same circles say smithsonite is linked to the heart chakra, helps process past emotional wounds and encourages forgiveness; they claim blue smithsonite brings calm and clarity and pink smithsonite love and compassion. There is no scientific evidence that smithsonite affects emotions or stress; lasting stress or emotional distress calls for help from a professional. Smithsonite is a zinc carbonate: the stone should not be put in water or an acidic liquid to make a drinkable “elixir”, and its dust should not be breathed in. This section reports beliefs; it is not health information. There is no scientific evidence for these claims and no stone replaces medical treatment.