Links

Some selected links are given as follows. Responsibility and access lies with the respective site owners.

http://www.zianet.com/geodekid/Gerard_Holzhey_Chem_Erde%202001.pdf

http://www.achatsammlung.de

http://www.agateworld.co.uk

http://www.achate.de

http://www.porphyrkugel.de/

http://snr.unl.edu/data/geologysoils/agates/index-agates.asp