Mineralogical Studies on Some Selected Semi-Precious Stones from Northeast Jordan
A semi-precious stone is known as a gem or gemstone (also a jewel, a gem, a
precious stone), which is a portion of mineral in refined and cut form that
could be used to create a jewelry or other embellishments. A gem also can be
defined as any mineral that is highly prized for its beauty, durability, and rarity,
is used for personal adornment and has been enhanced in some manner
by altering its shape usually by cutting and polishing. Semi-precious stones
occurred as xenolithes are widespread in Jordan within different source of
rocks. High grade of copper as malachite and chrysocolla and plancheite is
suitable for gemstone manufacture found in Finan area. High purity of garnet
can be found in metamorphic rocks in Wadi Araba area, whereas xenoliths of
pyroxene, olivine and spinel-perioditite and garnet are wide spread in basalt
and pyroclastic materials in northeast Jordan. The studied semi-precious
stones are part of the Miocene alkali basaltic rocks that covered the northeastern
part of Jordan within Harrat Al-Shaam Basaltic Super Group Plateau
concentrated mainly in volcanic centers and volcaniclastic materials of Aritian,
Hassan, Ufiyahim and Bishriyya formations. Some of these xenoliths
and xenocrysts can be considered as semi-precious stones. This study is focused
on characterization of petrography, mineralogy and geochemistry of
these semi-precious stones like olivine, pyroxene and garnet xenoliths that
have been collected from selected areas in northeast Jordan. The samples
were analyzed by polarizing microscope, X-Ray Diffraction (XRD), X-Ray
Fluorescence (XRF) and Scanning Electron Microscope (SEM). Cutting and
polishing tests have shown that some of the studied xenoliths are suitable for
manufacturing attractively colored gemstones and could be considered as
semi-precious stones. The geological chances for the discovery of some hundreds
of tons of these gemstone-raw materials are considered to be good in
volcaniclastic materials that are associated within different volcanic centers at