What does shocked quartz look like?
Shocked quartz is characterized by the presence of planar deformation features (PDFs)1. They consist of thin, straight, planar lamellae of amorphous or high-dislocation-density material, forming sets of features spaced 2–10 µm apart, oriented along rational crystallographic orientations, e.g., Refs.1,10.
What causes shocked quartz?
Lightning strikes can produce shocked quartz. Shocked quartz—whose crystalline structure is deformed along planes inside the crystal, a result of sudden high pressure and heating—long has been considered to be an unequivocal signature of the impact of an extraterrestrial object such as a meteorite.
How do you identify quartz in nature?
How to Identify Quartz
- A glassy luster.
- Hardness 7 on the Mohs scale, scratching ordinary glass and all types of steel.
- It breaks into curved shards rather than flat-faced cleavage fragments, meaning it exhibits conchoidal fracture.
- Almost always clear or white.
What is the streak color of quartz?
|Mohs scale hardness||7 – lower in impure varieties (defining mineral)|
|Luster||Vitreous – waxy to dull when massive|
|Diaphaneity||Transparent to nearly opaque|
Where can I find shocked quartz?
Commonly found in impact craters. Shocked quartz is often associated with the high-pressure silica polymorphs coesite and stishovite.
What happens to quartz under high pressure?
At low pressures (< 15 GPa), quartz transforms mostly by shear melting, while at higher pressures it converts mostly along transformation lamellae.
What is green quartz?
Green quartz is a macrocrystalline variety of the mineral quartz, the most abundant single mineral on earth. Most naturally occurring green quartz comes from a small mine in Brazil, with some minor deposits in Poland and Canada. Because natural green quartz is so rare, it is more commonly a heat-treated amethyst.
What is quartz breakage?
In the example below, quartz has a conchoidal (shell-shaped) fracture. Copper can have a jagged, hackly fracture. Cleavage and fracture are important tools you can use to identify minerals, but you don’t need to break your specimens to see this.
Where is stishovite found in nature?
The results are particularly exciting because stishovite is exactly the mineral found in shocked rocks at the Barringer Crater and similar sites across the globe. Indeed, stishovite (named after a Russian high-pressure physics researcher) was first found at the Barringer Crater in 1962.
What are shocked quartz crystals?
Shocked quartz crystals contained shocked lamellae, or small fractures that create lines in the quartz that go along the planes of the crystal. These planes can usually only be viewed under a microscope.
What is shock lamellae in quartz?
A variety of Quartz. Quartz shocked under intense pressure (but limited temperature). During the pressure shock, the crystalline structure of quartz will be deformed along planes inside the crystal. These planes, which show up as lines under a microscope, are called planar deformation features (PDFs), or shock lamellae.
When was shocked quartz first discovered?
Though shocked quartz is only recently recognized, Eugene Shoemaker discovered it prior to its crystallographic description in building stones in the Bavarian town of Nördlingen, derived from shock-metamorphic rocks, such as breccia and pseudotachylite, of Ries crater. ^ Eugene Merle Shoemaker (1959).
Does Lightning contribute to the surface record of shocked quartz?
Lightning is now known to contribute to the surface record of shocked quartz grains, complicating identification of hypervelocity impact features. Shocked quartz is usually associated in nature with two high-pressure polymorphs of silicon dioxide: coesite and stishovite. These polymorphs have a crystal structure different from standard quartz.