Quiz: Remember the definition of mal de mer?
titanium and calcium silicate mineral, CaTiSiO4(O,OH,F), that, in a crystallized or compact form, makes up a minor component of many igneous rocks and gneiss, schist, crystalline limestone, and pegmatite. Occurrences include the Tirol, Austria; Trentino, Italy; Norway; Switzerland; Madagascar; and the United States (New York). Titanite's relatively high dispersion causes it to be a brilliant gem of various colours; it is usually faceted. For detailed physical properties, see silicate mineral (table)