titanium fire; Class D dry powder agents must be used instead. When used in the production or handling of chlorine, titanium should not be exposed to dry chlorine gas because it may result in a titanium–chlorine fire. Titanium can catch fire when a fresh, non-oxidized surface comes in contact with liquid oxygen. Function in plants An unknown mechanism in plants may use titanium to stimulate the production of carbohydrates and encourage growth. This may explain why most plants contain about 1 part per million (ppm) of titanium, food plants have about 2 ppm, and horsetail and nettle contain up to 80 ppm. See also List of countries by titanium production Suboxide Titanium in Africa Titanium in zircon geothermometry Titanium Man VSMPO-AVISMA Footnotes References Bibliography External links "Titanium: Our Next Major Metal", Popular Science, October 1950—one of first general public detailed articles on Titanium Titanium at The Periodic Table of Videos (University of Nottingham) Titanium at The Essential Chemical Industry – online (CIEC Promoting Science at the University of York) International Titanium Association Metallurgy of Titanium and its Alloys, Cambridge University World Production of Titanium Concentrates, by Country Metal of the gods Aerospace materials Biomaterials Chemical elements with hexagonal close-packed structure Chemical elements Native element minerals Pyrotechnic fuels Transition metals