"Qaret-el-Hanash" structure in the Western Desert (Egypt)
(Probably the first detected
nearby the Silica strewnfield)
Norbert Brügge, Germany
Upload: April 2018
The Qaret-el-Hanash is a prominent doming structure with a wall on
top in the southeast direction of the Libyan Desert Glass area. The hight
of the hill is 96 m above ground. The slopes of the elevation are covered
with broken sandstones.
During an expedition in 1996 traces of an eroded zone of megascopic sandstone
breccia, of about 2-m thickness, have been recognized. The breccia occurs
within the wall of Qaret-el-Hanash. Its matrix appears as dull greyish-black
Petrographical and mineralogical studies have shown that there are breccias,
that consists of local sandstone rock fragments within a matrix of finer
quartz grains with glass and several other mineral phases. The results
were published in 2004 and declared as evidence of the emergence of Qaret-el-
Hanash by an impact (Aly Barakat).
However, the most important indication for the emergence of Qaret-el-Hanash,
which I postulate now as a eroded kimberlite pipe,
are the photos of Ursula Steiner (Switzerland), which come
from the top and outside slope of the structure and are available to me.
They document clear the subvolcanic origin of Qaret-el-Hanash impressively.
Some photos (below) show a strange, material of a dark (carbonaceous ?)
melt with included many diverse fragments, among ferruginous sandstone,
basement debris, glass and yellow jasper. The melt contain also visibly
large dark brown diamonds.
25°04'46"N / 25°56'02"E
Photos by Ursula Steiner (2012)
It looks like Barakat's "black rock" (Hypatia stone) but with a lot of
brecciated material from the depths (basement debris, glass, jasper etc.).
The structure is crater-shaped, as it occurs in the Gilf Kebir Crater
Field (GKCF), but without (and that is the significant difference) the
tilted layers on the edge, indicating an explosion. It seems that the
most of "black rock" material is burned ferruginous sandstone.
But a black glassy (carbonaceous
solutions are also involved.
The whole composition is chaotic. At
the place of the debris, near the southwestern slope, were also found
visibly large dark brown diamonds. The exact coordinates are known to
DISCOVERY OF Fe-Cr-Ni SPECKS WITHIN QARET EL-HANASH
BRECCIA OF THE LIBYAN GLASS AREA SOUTH WESTERN EGYPT
A. El-Kammar, I. Arafa, K. A. Soliman & A. Barakat --7th International
Conference on the Geology of the Arab World, Cairo University, Feb.
2004, P. 1-7
The rock consists of various fragments of local sandstone,
i.e., from the area of the glass distribution itself. Fragments of
igneous source have never been recorded. The rock fragments range
from fraction of mm up to 4-cm in diameter, in the collected specimens.
The rock fragments vary in colour from creamy white to brownish-red.
They are angular to subrounded and embedded in a dull greyish-black
matrix. The microscopic investigation and scanning electron microanalysis
confirmed the above-mentioned observation and showed that the matrix
consists of shattered and fragmented quartz grains of various sizes.
In addition to quartz, the matrix contains many other phases, such
as glass, zircon, clay minerals, wollastonite, ilmenite, Mg-ilmenite,
rutile and Fe-Cr-Ni specks.
There are several metallic specks of various
sizes ranging from 1 micron up to about 10 micron, dispersed in the
matrix of Qaret el Hanash breccia. They invade some of the quartz
grains. These specks are mainly of irregular outlines and some of
them show clear fissures. They are associated with glass and intercalated
in some cases with halite. EDAX analyses of such specks indicate that
they consist of native Fe, Cr and Ni, in addition to subordinate Si
and Ca. Finer particles of similar appearance have also been noticed
by the petrographical microscope through the fractures of some of
the quartz grains.
The most interesting achievement of the chemical
analyses is the detection of high Ir content (2.0-2.2 ppb) within
the breccias. This value represents the highest reported values for
the area. The reported value of Ir in other breccias in the area is
around 1.6-1.9 ppb. The highest reported concentration of Ir by the
previous studies was detected from the black streak portions from
the Libyan glass itself is 1.25 ppb. (Barakat 2018)
Personal information by Aly Barakat on May 19, 2018: The samples
contains tiny particles of Fe-Cr-Ni, and other phases includes tiny
grains of moissanite and diamond.