Rare AZUARA, SPAIN Impactite PITTED & SHATTERED Cobblestone 186-gram (6.5-oz.)

Description

Roughly 30 to 40-million years ago, during the Upper Eocene or Oligocene, twin asteroids apparently slammed simultaneously into nearby areas of Spain. The resultant cratering is now known as the Rubielos de la Cérida Basin and the Azuara impact crater.
The shock of the large meteorite or
asteroid impacts caused piles of quartzite river cobbles to smash into each other violently and reverberate, creating numerous spallations or circular pits where the rounded portions struck each other. The whitish color results from micro-fracturing on the areas of contact. Some, such as this superb specimen, were shattered, but remained whole as the slices apparently melted together. High-speed fine dust from the impact blasted many of the very hard pebbles causing them to become highly polished. Over time, the cobbles became cemented together forming Buntsandstein conglomerates and eventually these hard cobbles weathered out. Today they are found exposed around the Rubielos de la Cérida impact basin. Individual stones typically feature craters, the pockmarks known as spallations, and fractures. THIS specimen shows a many fractures. It is about 7.1 x 5.0 x 3.0-cm (~ 0.4 x 2.0 x 1 1/2-inches and weighs 186.0-grams (6 1/2-oz.).
I will ship this via First Class Mail within the USA. I can also combine other winnings and ship in the same carton to save you postage.
There is, quite understandably, a growing interest in large meteorites and asteroids. That such large objects have struck all the moons and planets in the Solar System, including Earth in the past, and will continue to do so in future, is something scientists have only begun to recognize since about 1980.
At present, there are nearly 200 recognized impact structures, and, every year, one or two new ones are being confirmed. Perhaps one hundred potential sites awaiting study. Confirmation of new impact craters takes a lot of time because there are probably more workers at the average McDonald's Restaurant than impact crater geologists!
Asteroids and comets have struck Earth many millions of times over the last 3.5-billion (3.5-thousand million) years, leaving impact craters that, over time, have for the most part eroded away. Long after these impact craters have disappeared from the landscape, local or area rocks and soil affected by the impacts, known as
impactites
, may yet remain.
The impact creates a crater far larger than the size of the impacting body. Local and area rock and soil are vaporized. Small craters resemble simple bowls; larger ones may contain a central uplift or peak and multiple rings. Melted fragments may be tossed at high speed becoming aerodynamically-sculpted as impact melt glass bombs. Or the soil and sand may quickly cool into impact melt glass.
IMPACTITES may be mixtures of local
shattered and melted rock and dust deposited many kilometers
or miles
away. These mixtures
may harden into a new rock type called impact breccia or fallback breccia. Monomict breccia has
only one variety of rock fragments
within a fine-grained matrix. Polymict breccia has two or more varieties of rock f
ragments within a fine-grained matrix.
Molten sand and soil may quickly cool into layers of impact melt glass. Some of the melted fragments may be tossed
at high
speed becoming aerodynamically-sculpted. These are known as impact melt glass bombs and impact melt glass.
Some show
signs of having been twice melted: first, thrown out of the lower atmosphere, then aerodynamically-
sculpted returning to Earth,
often landing many kilometers or miles from the impact. Such very dry natural glasses are
called tektites. Those found mainly
in the Czech Republic are called Moldavites and originated from the Ries, Germany impact.
Bediasites found in Texas and
Georgiaites
in Georgia, USA are tektites originating from the Chesapeake Bay, USA impact crater. The Australasian strewn
field
is the largest and geologically youngest of the tektite strewn fields and the only one
thus far with no confirmed
associated
impact
crater
. Layered Moung Nong tektites found in Eastern Laos such as the one here show no sign of flight.
It is possible to find minerals morphed by the pressure of impact v
isible only under a microscope under polarized light.
These
are generally referred to as shocked quartz. Quartz grains in sand may be morphed into minerals such as
coesite or
Stishovite.
There are also occasional and unusual rock types generally associated with impact craters. Examples include Missouri
Round
Rocks from Weaubleau, Missouri, shocked and sliced fossils from Ries, Germany, high-carbon anthraxolite from Sudbury,
Ontario, Canada, rocks sliced and melted back together from
Rubielos
de la Cérida
and Azuara, Spain, and pseudotachylite,
a rock type caused by massive friction of rocks against one another during or shortly after such impacts.