Nitrous oxide (Popularity: ): The history and importance of "Laughing Gas." Amethyst (Popularity: ): Amethyst is a variety of quartz with purple coloration which is caused by impurities of iron or manganese. Salt (Popularity: ): Physiology, geology, economics, religion, production, etymology and anything else you might want to know about sodium chloride. Ferrocene (Popularity: ): Unusually stable, with structure and bonding that defies conventional bonding descriptions. Bioinorganic Gallery (Popularity: ): Hyperactive Bioinorganic Proteins. A Chemical MIME & Picture Gallery. VRML Gemstones (Popularity: ): A collection of gemstone information and coordinates as VRML files. Water (Popularity: ): Importance and biophysical properties of water. Wilkinson's Catalyst (Popularity: ): Organometallic compound that activates small organic molecules such that bond-breaking and bond-formation pathways are readily accessible. ZSM-5a Zeolite Catalyst (Popularity: ): Heterogeneous catalysts useful in the interconversion of hydrocarbons and the alkylation of aromatic compounds. Metal Carbonyls (Popularity: ): 3D structure and bonding patterns of metal carbonyls.