Definition of "ruthenium" [ru•the•ni•um]

• A hard silver-gray acid-resistant metallic element that is found in platinum ores and is used to harden platinum and palladium for jewelry and in alloys for nonmagnetic wear-resistant instrument pivots and electrical contacts. Atomic number 44; atomic weight 101.07; melting point 2,310°C; boiling point 3,900°C; specific gravity 12.41; valence 0, 1, 2, 3, 4, 5, 6, 7, 8. See Table at element. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Electro-deposition using black rhodium or ruthenium is the first technique."
• "Many of our advances in ruthenium catalyst development were the result of applying the techniques developed earlier in our group in the study of other complex catalytic processes."
• "One of the best examples in recent years, tetracarbonly-diruthenium fulvalene, requires the use of ruthenium, which is rare and expensive."