Lesson C5.4 http://www.mpcfaculty.net/mark_bishop/precipitation.htm
Lesson C5.5 http://www.dwi.gov.uk/index.htm
Lesson C5.6 http://www.ch.cam.ac.uk/teaching/crystals
Lesson C5.8 www.rsc.org/education/teachers/resources/alchemy
Lesson C5.10 www.rsc.org/education/teachers/resources/alchemy
Lesson C5.11 http://www.leadminingmuseum.co.uk/Gold_Facts.htm
http://facts.randomhistory.com/2009/03/09_gold.html
http://www.facts-about.org.uk/science-element-gold.htm
www.responsiblegold.org
