- Black Wednesday (folklore.org)
I could tell there was something wrong from the moment I stepped into the building, on the morning of Wednesday, February 25th, 1981. Instead of the normal office buzz, there was a muted sadness hanging in the air. People were standing around, huddled in small groups. I ran into Donn Denman, who had a cubicle near mine, and asked him what was going on.
- Chert (Wikipedia)
Chert (/ˈtʃɜːrt/) is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a chemical precipitate or a diagenetic replacement, as in petrified wood.