What is "Shocked Quartz"?

Question

I am learning about meteorites. Some of the descriptions of various meteorites mention that the specimen has "Shock Lines"

What does this mean and what does it look like?

Answer 1

They are striations in the stone cause by some type of shock event. Could be either entering the atmosphere, hitting the earth, or something that happened extraterrestrially.


Here's a couple of photos

http://cgi.ebay.com/500-GR-UNCLASSIFIED-METEORITE-ENDCUT-SHOCK-LINES-METAL_W0QQitemZ260013901880QQcmdZViewItem

Answer 2

Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. Under intense pressure (but limited temperature), the crystalline structure of quartz will be deformed along planes inside the crystal. These planes show up as lines under a microscope, which are called shock lamellae.


Shocked quartz is associated with two pressure polymorphs of silicon dioxide: coesite and stishovite. These polymorphs have a different molecular structure than standard quartz. Again, this structure can only be formed by intense pressure, but moderate temperatures. High temperatures would anneal the quartz back to its standard form. Coesite and stishovite are thus also indicative of impact (or nuclear explosion).

THE SHOCK LINES:
Small parallel lines that intersect other parallel lines criss-crossed the face of the grains. These intersecting lines give the impression of fractures in the quartz, but a structural analysis (X-ray diffraction analysis) of these grains showed that the crystalline lattice is only slightly deformed, and it isn't fractured. These microscopic lines (actually, they are planar features) were named "shock lamellae" (lamellae is pronounced "la-MEL-ee").

Answer 3

Shocked quartz
Shocked quartz (or Stishovite) is a high pressure polymorph of quartz produced at or close to the impact site. It is produced under such high pressurs that the only way it can form is by cosmic impacts. Finding traces of this in any geological strata is a very good indicator of an impact. Shocked quartz grains can only usually be seen with a scanning electron microscope.

Answer 4

I saw this on the Discovery channel the other day. I seem to remember that the crystal array in the quartz all line up in one direction ...