Located in a Mexican town called Naica (as shown in map)
The town was built around the abundance of precious minerals to be mined
The crystals in the cave were formed from volcanic eruptions and a lot of time
There are actually three linked but separate caves
The lowest cave has the largest crystals
The lowest cave has insane temperatures that humans cannot survive in for long
Links for photos
https://www.bing.com/images/search?q=crystal+cave&view=detailv2&&id=DB38726987B9D3D4C1A8E51BC0068117483DAFCF&selectedIndex=3&ccid=qxOMjx%2fL&simid=608017390112345435&thid=OIP.Mab138c8f1fcbadc15cde45f0d3d46449o0
https://www.google.ca/imgres?imgurl=http%3A%2F%2Fstatic.thousandwonders.net%2FChihuahua.original.1263.jpg&imgrefurl=http%3A%2F%2Fwww.thousandwonders.net%2FNaica%2BMine&docid=VpIh2OdXix4aAM&tbnid=gfLAftfhXRrKdM%3A&vet=1&w=1600&h=1066&safe=active&bih=651&biw=1366&ved=0ahUKEwjCwtOamdHQAhUp_4MKHWhaBLQQMwg-KBYwFg&iact=mrc&uact=8
https://www.bing.com/images/search?q=entrance+to+naica+mine&id=F3681494EFBDC4B0A88BBFD368AC89DEB160C4AE&FORM=IQFRBA