Lizardite

Lizardite is a magnesium phyllosilicate, Mg3Si2O5(OH)4, and the most abundant member of the serpentine group, alongside chrysotile and antigorite. First described in 1956 from Cornwall's Lizard Peninsula, England — its type locality and namesake — lizardite forms through retrograde metamorphism and hydrothermal alteration of olivine, enstatite and other ferromagnesian silicates in ultramafic rocks, typically intergrown with brucite, magnetite, chromite and talc within serpentinite and ophiolite bodies. It crystallizes as fine-grained, platy or foliated masses rather than large individual crystals, usually in shades of green, olive, yellow-green or near-white, with a distinctive waxy to greasy, soapy-feeling luster. Pseudomorphs after enstatite, olivine or pyroxene — known as bastite — are a particularly sought-after collector habit, showcasing the mineral's replacement textures at a glance.

The type locality at Kennack Cove on the Lizard Peninsula remains the benchmark for well-documented lizardite, with additional classic British material recorded on Unst in Scotland's Shetland Islands and at Holy Island, Anglesey in Wales, where it replaces primary olivine and orthopyroxene in serpentinized peridotite. Fine crystallographic reference material comes from Elba, Italy, and from northern Apennine ophiolites near Modena, while Italian specimens are also documented from the Sissone Valley in Valmalenco, Sondrio, and the Val Munari area near Vicenza. Norway contributes notable pieces from the Dypingdal serpentine-magnesite deposit near Modum, sometimes showing lizardite alongside hematite and hydrotalcite. In the United States, lizardite occurs along the north shore of Lake Superior in Minnesota, within the Stillwater Complex of Montana, and at Nottingham County Park in Pennsylvania, where it is the dominant serpentine species. A single specimen has even been documented from altered pegmatite at Mont Saint-Hilaire, Quebec. South Africa's Wessels mine and Frank Smith mine in the Kalahari Manganese Field are notable for striking orange lizardite, a gemological curiosity prized well beyond typical serpentine green.

Collectors value lizardite both for its geological storytelling — it records the serpentinization of oceanic and mantle rock, a process linked to hydrogen generation and even deep-subsurface microbial ecosystems — and for the visual variety it offers, from soft bastite pseudomorphs to polished serpentine masses and rare orange or near-white colorations. Because it can form a solid-solution series with the nickel-bearing népouite, and shares its formula with the polymorphs chrysotile and antigorite, lizardite is also a favorite reference species for mineralogists studying serpentine polytypism, alongside associated minerals like magnesite, dolomite and hydrotalcite found in the same serpentinite assemblages.