References:
http://www.opalsdownunder.com.au/learn-about-opals/intermediate/how-opal-mined
http://www.opalsdownunder.com.au/learn-about-opals/intermediate/australian-opal-mining-fields
http://nz.southaustralia.com/info.aspx?id=9006369
https://www.youtube.com/watch?v=urpV5C7PQG4
http://www.dailymail.co.uk/news/article-2772720/The-eerie-world-underground-Coober-Pedy-town.html
https://www.cooberpedy.sa.gov.au/page.aspx?u=368#.VbxD1pOqqkp
http://www.cooberpedy.net/opals/coober-pedy-profile
http://www.kingopal.com.au/opal-formation.php
https://www.youtube.com/watch?v=gfzMMX8tkl4
https://www.cooberpedy.sa.gov.au/page.aspx
http://www.southaustralianhistory.com.au/cooberpedy.htm
http://www.bbc.com/news/science-environment-32665035
http://www.abc.net.au/science/ozfossil/ageofreptiles/eromanga/default.htm
http://www.safeworkaustralia.gov.au/sites/SWA/model-whs-laws/public-comment/Documents/Mining%20Public%20Comment%202011/Public%20submissions%20N/022%20-%20National_Opal_Miners_Association.pdf
http://www.extension.umn.edu/agriculture/tillage/soil-compaction/
http://www.aridareastours.com/about/
http://www.adelaidenow.com.au/news/south-australia/opal-inn-roof-dislodged-as-135kmh-winds-leave-coober-pedy-buildings-in-ruins/story-fni6uo1m-1227109076340
http://www.gia.edu/cs/Satellite?c=GIA_Video&childpagename=GIA%2FGIA_Video%2FMediaDetail&cid=1363399450045&pagename=GST%2FDispatcher
http://www.maqohsc.sa.gov.au/_upload_docs/20090216064054.OpalMining.pdf
http://www.lung.org/lung-disease/silicosis/understanding-silicosis.html?referrer=https://www.google.co.nz/
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5416a2.htm
http://www.allcountries.org/health/silicosis.html
http://newartcolorz.com/cat/4/213374.html
https://www.flickr.com/photos/edenink/5980452107
https://lovethesepicture.wordpress.com/2011/09/15/sacred-uluru-the-ancient-heart-of-australia-41-pics/
http://andersonaustraliatrip2011.blog.com/files/2011/09/coober-pedy-for-blog.jpg
http://www.theaustralian.com.au/life/travel/photos-fn3025xv-1225927841286?page=16
http://www.opalsdownunder.com.au/learn-about-opals/intermediate/australian-opal-mining-fields
http://nz.southaustralia.com/info.aspx?id=9006369
https://www.youtube.com/watch?v=urpV5C7PQG4
http://www.dailymail.co.uk/news/article-2772720/The-eerie-world-underground-Coober-Pedy-town.html
https://www.cooberpedy.sa.gov.au/page.aspx?u=368#.VbxD1pOqqkp
http://www.cooberpedy.net/opals/coober-pedy-profile
http://www.kingopal.com.au/opal-formation.php
https://www.youtube.com/watch?v=gfzMMX8tkl4
https://www.cooberpedy.sa.gov.au/page.aspx
http://www.southaustralianhistory.com.au/cooberpedy.htm
http://www.bbc.com/news/science-environment-32665035
http://www.abc.net.au/science/ozfossil/ageofreptiles/eromanga/default.htm
http://www.safeworkaustralia.gov.au/sites/SWA/model-whs-laws/public-comment/Documents/Mining%20Public%20Comment%202011/Public%20submissions%20N/022%20-%20National_Opal_Miners_Association.pdf
http://www.extension.umn.edu/agriculture/tillage/soil-compaction/
http://www.aridareastours.com/about/
http://www.adelaidenow.com.au/news/south-australia/opal-inn-roof-dislodged-as-135kmh-winds-leave-coober-pedy-buildings-in-ruins/story-fni6uo1m-1227109076340
http://www.gia.edu/cs/Satellite?c=GIA_Video&childpagename=GIA%2FGIA_Video%2FMediaDetail&cid=1363399450045&pagename=GST%2FDispatcher
http://www.maqohsc.sa.gov.au/_upload_docs/20090216064054.OpalMining.pdf
http://www.lung.org/lung-disease/silicosis/understanding-silicosis.html?referrer=https://www.google.co.nz/
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5416a2.htm
http://www.allcountries.org/health/silicosis.html
http://newartcolorz.com/cat/4/213374.html
https://www.flickr.com/photos/edenink/5980452107
https://lovethesepicture.wordpress.com/2011/09/15/sacred-uluru-the-ancient-heart-of-australia-41-pics/
http://andersonaustraliatrip2011.blog.com/files/2011/09/coober-pedy-for-blog.jpg
http://www.theaustralian.com.au/life/travel/photos-fn3025xv-1225927841286?page=16