The third round of ABC Wednesday has reached the letter O this week.
In keeping with my love of rocks and gemstones,
Funnily enough, obsidian isn't strictly speaking a rock. It's a naturally occurring glass, formed in volcanos.
More details here.
Although it can appear brown and even appear to have a metallic coating, obsidian is generally thought of as black. Being a glass, it takes a very sharp edge, and was used by the Incas in ceremonial knives.
My samples are a variety known as Snowflake Obsidian because of the whitish included crystals which can look like snowflakes.
ABC Wednesday was started by Mrs Nesbitt. More O posts can be found on the Anthology Page and through the Linky site.