Columnar basalt is not the same as petrified wood….which is generally quartz chalcedony.
Still in shock after watching MM movie….
https://twitter.com/billmckibben/status/1256322296039436289?s=20
https://twitter.com/GretaThunberg/status/1256652029591793666?s=20
Still trying to decide which of the three causes that tweet is really about.