Green Tourmaline

Green tourmaline, the variety called verdelite, belongs to the tourmaline group, a boron-rich silicate whose crystals grow as long prisms with a distinctive rounded-triangular cross-section and heavy lengthwise striations. Its green comes from iron or chromium, and single crystals often shift colour along their length or from core to rim, which is why tourmaline yields the famous watermelon stones with a pink centre and green skin.

Like all tourmaline it is pyroelectric and piezoelectric, developing an electric charge under heat or pressure. Tourmaline was not clearly distinguished as a species in Europe until the eighteenth century, when rough was brought from Sri Lanka by Dutch traders, so its gem history is comparatively short and much older emerald in historical accounts may sometimes have been green tourmaline. Its modern metaphysical placement with the heart centre follows from the colour and dates from the twentieth century.