Liddicoatite: Vibrant Gem Honours Father of Modern Gemology

Most liddicoatite comes from Madagascar, including this slice from the Anjanabonoina pegmatite. Coutresy Harvard Mineralogical Museum, photo by Robert Weldon/GIA
Liddicoatite – a calcium-rich lithium tourmaline – is revered for its complex colour zoning that often displays several vibrant colours. The common trigonal pattern comes to life when the gem is fashioned as polished slices that highlight the characteristic red, purple, green and yellow hues of this striking gem. Multicoloured zoning – what gemmologists refer to as parti-coloured – occurs when the trace elements change in concentration or composition during a crystal’s growth.

First recognised as a separate mineral in 1977, liddicoatite was named in honour of Richard T. Liddicoat (2 March 917 – 23 July 2002), the second president of GIA who is often referred to as the “Father of Modern Gemology”. Dr Pete J. Dunn and his colleagues from the U.S. National Museum of Natural History identified liddicoatite as a distinct mineral and chose the name in recognition of Liddicoat’s many contributions to gemmological knowledge and education, including his creation of the International Diamond Grading System and its well-known and universally recognised scales for measuring the colour and clarity of diamonds.

Liddicoatite – along with elbaite, dravite, uvite and schorl – is one of the major tourmaline species. Its appearance is similar to elbaite, and it can only be distinguished through chemical analysis. Most known liddicoatite comes from the Anjanabonoina pegmatites in central Madagascar.

These liddicoatite slices were displayed at GIA in Carlsbad in honour of Richard T. Liddicoat's birthday. Photo by Kevin Schumacher/GIA