Whilst hiking at Dolly Sods over the weekend, I found this old artifact:
Upper 10 is apparently a “Sprite”-esque lemon-lime soda, discontinued in America but still being marketed abroad. But that wasn’t what got me jazzed, of course. Look more closely…
That is a lovely little conchoidal fracture, and it’s so exquisite because it preserves not only the concentric “ribs” that are typical of conchoidal fractures, but also delicate little traces of plumose structure. Note that the conchoidal “ribs” are parallel to the advancing joint front (leading edge of the fracture), and the plumes are perpendicular to the joint front.
Thank you, Upper 10, and thank you, nameless Dolly Sods litterbug, for providing us with this fine lesson in fracture anatomy.