Copper

It's Elemental: Copper - Basic physical and historical information.
http://education.jlab.org/itselemental/ele029.html

Visual Elements: Copper - Image, general and physical information, source, uses, key isotopes, and ionisation energies.
http://www.chemsoc.org/viselements/pages/copper.html

LANL: Copper - History, properties, sources, and uses.
http://periodic.lanl.gov/elements/29.html

Copper - Properties and applications along with photographs and chemical formulas of occurrences.
http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e02900.html

WebElements: Copper - Extensive information on history, uses, occurrence, compounds, and properties of the element.
http://www.webelements.com/webelements/elements/text/Cu/key.html

ChemicalElements.com: Copper - Basic information, atomic structure, and table of isotopes.
http://www.chemicalelements.com/elements/cu.html

Lenntech: Copper - Physical data, chemical properties, health and environmental effects.
http://www.lenntech.com/Periodic-chart-elements/Cu-en.htm

Radiochemistry of Copper - Full text of the monograph by F. F. Dyer (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF] <small>(April, 1961)</small>
http://library.lanl.gov/cgi-bin/getfile?rc000048.pdf

ChemGlobe: Copper - Electronic, thermal, and steric data along with an isotope table.
http://partisans.spurious.biz/~pkremer/projects/chemglobe/ptoe/_/29.html

EnvironmentalChemistry.com: Copper - Atomic structure, chemical and physical properties, and table of nuclides.
http://environmentalchemistry.com/yogi/periodic/Cu.html

USGS Minerals Information: Copper - Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
http://minerals.usgs.gov/minerals/pubs/commodity/copper/

Wikipedia: Copper - Properties of the element, including its history, applications, and characteristics.
http://en.wikipedia.org/wiki/Copper