chromium

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A lustrous, hard, steel-gray metallic element, resistant to tarnish and corrosion and found primarily in chromite. It is used in the hardening of steel alloys and the production of stainless steels, in corrosion-resistant decorative platings, and as a pigment in glass. Atomic number 24; atomic weight 51.996; melting point 1,890°C; boiling point 2,482°C; specific gravity 7.18; valence 2, 3, 6. See Table at element.

Century Dictionary and Cyclopedia

1. n. Chemical symbol, Cr; atomic weight, 52.3; specific gravity, 6.8-7.3. An element belonging to the metals, obtained in the pure state as a light-green crystalline powder. The separate crystals under the microscope have a tin-white color. It is less fusible than platinum, and after fusion is harder than corundum. It oxidizes slowly in the air, but burns vividly in oxygen. Hot hydrochloric or sulphuric acid dissolves it; nitric acid does not affect it. Chromium does not occur native. It is found in the mineral crocoite or crocoisite (lead chromate), and as a sulphid in daubreelite; it occurs also in some meteoric iron, and the fine green color which makes the emerald valuable is believed to be due to chromium; but the most abundant ore of chromium is chromite or chrome-ironstone. Among its most important compounds are the oxid or sesquioxid (Cr₂O₃), which occurs native in chrome-ocher and chromite. It is a dull-green powder when made artificially by reduction of the chromates, and is used extensively for imparting a green color to porcelain and enamel, and somewhat as a pigment, in the form of chromic oxid, under the name of Guignet's green. Potassium bichromate (k₂Cr₂O₇) is the salt from which most salts of chromium are prepared. It forms garnet-red crystals, which dissolve in water, making a red solution. It is largely used in dyeing and calico-printing and as an oxidizing agent; also in the carbon or other processes of photographic printing, and in a form of voltaic cell called the bichromate cell. See cell, 8. It is an active poison.

Wiktionary

1. n. A metallic chemical element (symbol Cr) with an atomic number of 24.

GNU Webster's 1913

1. n. (Chem.) A comparatively rare element occurring most abundantly in the mineral chromite. Atomic weight 52.5. Symbol Cr. When isolated it is a hard, brittle, grayish white metal, fusible with difficulty. Its chief commercial importance is for its compounds, as potassium chromate, lead chromate, etc., which are brilliantly colored and are used dyeing and calico printing. Called also chrome.

WordNet 3.0

1. n. a hard brittle multivalent metallic element; resistant to corrosion and tarnishing