8 September 2010

Lessons from a broken bottle

Posted by Callan Bentley

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.

Here’s an annotated copy to make this more explicit:

The same pattern can be observed in a second fracture, this one located within the glass (not on the surface):

Annotated copy:

Nice! This is the same pattern that we observe with the fine-scale topography of joint surfaces in rocks, as I have blogged on several occasions.

Thank you, Upper 10, and thank you, nameless Dolly Sods litterbug, for providing us with this fine lesson in fracture anatomy.