Listing description
Jasper, a form of chalcedony, is an opaque, impure variety of silica, usually red,
yellow, brown or green in color. Blue is rare. This mineral breaks with a smooth surface, and is
used for ornamentation or as a gemstone. It can be highly polished and is
used for vases, seals, and at one time for snuff
boxes. When the
colors are in stripes or bands, it is called striped or banded
jasper. Jaspilite is a banded
iron formation rock
that often has distinctive bands of jasper
Detailed description
Jasper, a form of chalcedony,[1]
is an opaque,[2]
impure variety of silica, usually red, yellow, brown or green in color. Blue is rare. This mineral breaks
with a smooth surface, and is used for ornamentation or as a gemstone. It can
be highly polished and is used for vases, seals, and at
one time for snuff boxes. When the colors are in stripes or bands, it is called striped
or banded jasper. Jaspilite is a banded iron formation rock that often has distinctive bands of jasper. Jasper is
basically chert which
owes its red color to iron(III)
inclusions. The specific gravity
of jasper is typically 2.5 to 2.9.[3]
The jasper is also a stone in the Jewish High Priest's
breastplate,
described in Exodus 28.
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Etymology
and history
The name means "spotted or
speckled stone", and is derived via Old French jaspre (variant of Anglo-Norman jaspe) and Latin iaspidem (nom. iaspis))
from Greek ἴασπις
iaspis, (feminine noun)[4]
from a Semitic language (cf. Hebrew ישפה yashepheh,
Akkadian ܝܫܦܗ
yashupu), ultimately from Persian یشپ yašp.[5]
Green jasper was used to make bow drills
in Mehrgarh between
4th-5th millennium BC.[6]
Jasper is known to have been a favorite gem in the ancient world; its name can
be traced back in Hebrew, Assyrian, Persian, Greek
and Latin.[7]
On Minoan Crete within present day Greece jasper was carved to produce seals circa 1800 BC based upon
archaeological recoveries at the palace of Knossos.[8]
Types
Jasper is an opaque rock of
virtually any color stemming from the mineral content of the original sediments
or ash. Patterns arise during the consolidation process forming flow and
depositional patterns in the original silica rich sediment or volcanic ash.
Hydrothermal
circulation is generally thought to be required
in the formation of jasper.[citation needed]
Jasper can be modified by the
diffusion of minerals along discontinuities providing the appearance of
vegetative growth, i.e., dendritic. The original materials are often fractured and/or
distorted, after deposition, into myriad beautiful patterns which are to be
later filled with other colorful minerals. Weathering, with time, will create
intensely colored superficial rinds.
The classification and naming of
jasper presents a challenge.[9]
Terms attributed to various well-defined materials includes the geographic
locality where it is found, sometimes quite restricted such as
"Bruneau" (a canyon) and "Lahontan" (a lake), rivers and
even individual mountains, many are fanciful such as "Forest Fire" or
"Rainbow", while others are descriptive such as "Autumn", "Porcelain"
or "Dalmatian". A few are designated by the country of origin such as
a Brown Egyptian or Red African leaving tremendous latitude as to what is
called what.
Picture jaspers exhibit combinations
of patterns (such as banding from flow or depositional patterns (from water or
wind), dendritic or color variations) resulting in what appear to be scenes or
images, on a cut section.[10]
Diffusion from a center produces a distinctive orbicular appearance, i.e.,
Leopard Skin Jasper, or linear banding from a fracture as seen in Leisegang
Jasper. Healed, fragmented rock produces brecciated
(broken) jasper. Examples of this can be seen at Llanddwyn Island
in Wales.
Chalcedony (pronounced /kælˈsɛdəni/) is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite.[2] These
are both silica minerals, but they differ in that quartz has a trigonal
crystal structure, whilst moganite is monoclinic.
Chalcedony's standard Chemical structure (Based on the chemical structure of quartz) is SiO2
(Silicon Dioxide).Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black.
The name "chalcedony" comes from Latin calcedonius, the word used to translate the Greek word khalkedon, found only once, in the Book of Revelation; according to the OED a connection with the town of Chalcedon in Asia Minor is "very doubtful".[3] There is no reason to assume that the precious stone referred to by this name in the Bible is the same as what is now understood by the name.[4]
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Varieties
Chalcedony occurs in a wide range of
varieties. Many semi-precious gemstones
are in fact forms of chalcedony. The more notable varieties of chalcedony are
as follows:
Agate
Agate is
a variety of chalcedony with multi-colored curved or angular banding. Fire
agate shows iridescent phenomena on a brown background; iris agate shows
exceptional iridescence when light (especially pinpointed light) is shone
through the stone. Landscape agate is chalcedony with a number of different
mineral impurities making the stone resemble landscapes.[5]
Aventurine
Aventurine is a form of quartz, characterised by its
translucency and the presence of platy mineral inclusions that give a shimmering or glistening effect termed aventurescence.The most common colour of aventurine is green, but it may also be orange, brown, yellow, blue, or gray. Chrome-bearing fuchsite (a variety of muscovite mica) is the classic inclusion, and gives a silvery green or blue sheen. Oranges and browns are attributed to hematite or goethite. Because aventurine is a rock, its physical properties vary: its specific gravity may lie between 2.64-2.69 and its hardness is somewhat lower than single-crystal quartz at around 6.5.
Aventurine feldspar or sunstone can be confused with orange and red aventurine quartzite, although the former is generally of a higher transparency. Aventurine is often banded and an overabundance of fuchsite may render it opaque, in which case it may be mistaken for malachite at first glance.
The name aventurine derives from the Italian "a ventura" meaning "by chance". This is an allusion to the lucky discovery of aventurine glass or goldstone at some point in the 18th century. Although it was known first, goldstone is now a common imitation of aventurine and sunstone. Goldstone is distinguished visually from the latter two minerals by its coarse flecks of copper, dispersed within the glass in an unnaturally uniform manner. It is usually a golden brown, but may also be found in blue or green.
History
As early as the Bronze Age
chalcedony was in use in the Mediterranean
region; for example, on Minoan Crete at the Palace of Knossos,
chalcedony seals have been recovered dating to circa 1800 BC.[6]
People living along the Central Asian
trade routes used various forms of chalcedony, including carnelian,
to carve intaglios, ring bezels (the upper faceted portion of a gem
projecting from the ring setting), and beads that show strong Graeco-Roman
influence.Fine examples of first century objects made from chalcedony, possibly Kushan, were found in recent years at Tillya-tepe in north-western Afghanistan.[7] Hot wax would not stick to it so it was often used to make seal impressions. The term chalcedony is derived from the name of the ancient Greek town Chalkedon in Asia Minor, in modern English usually spelled Chalcedon, today the Kadıköy district of Istanbul.
At least three varieties of chalcedony were used in the Jewish High Priest's Breastplate. (Moses' brother Aaron wore the Breastplate, with inscribed gems representing the twelve tribes of Israel). The Breastplate included jasper, chrysoprase and sardonyx, and there is some debate as to whether other agates were also used.
In the 19th century Idar Oberstein became the world's largest chalcedony processing center, in particular agates. Most of these agates were sourced in Latin America, in particular Brazil. Originally the agate carving industry around Idar and Oberstein was driven by local deposits that were mined in the 15th century.[8] Several factors contributed to the re-emergence of Idar-Oberstein as agate center of the world: ships brought agate nodules back as ballast, thus providing extremely cheap transport. Cheap labor and a superior knowledge of chemistry allowing them to dye the agates in any color with processes that were kept secret.
Each mill in Idar Oberstein had four or five grindstones. These were of red sandstone, obtained from Zweibrücken; and two men ordinarily worked together at the same stone.[8]
Geochemistry
Structure
Chalcedony was once thought to be a fibrous
variety of cryptocrystalline quartz.[9]
More recently however, it has been shown to also contain a monoclinic
polymorph of quartz,
known as moganite.[2]
The fraction, by mass, of moganite within a typical chalcedony sample may vary
from less than 5% to over 20%.[10]
The existence of moganite was once regarded as dubious, but it is now
officially recognised by the International
Mineralogical Association.[11][12]
Solubility
Chalcedony is more soluble than
quartz under low-temperature conditions, despite the two minerals being
chemically identical. This is thought to be because chalcedony is extremely
finely grained (cryptocrystalline), and so has a very high surface area to
volume ratio.[citation needed] It has also
been suggested that the higher solubility is due to the moganite component.[10]
Solubility of quartz
and chalcedony in pure water
This table gives equilibrium concentrations
of total dissolved silicon as calculated by PHREEQC using the llnl.dat database[citation needed].
Packaging
details
We usually
bag ores in 50kg,100kg,150kg and 200kgs depending on specifications. Now for a
50kg bagged ore it will contain 480 bags for a 20ft container,610 bags for a
40ft container, 642 and 674 bags for a
48ft and 53ft containers respectively. For a 100kg bagged ore we have 240 bags for a 20ft container, 305 bags
for a 40ft container,329 bags for
48ft and 344 bags for a 53ft
container. However, the best method to transport ores such as iron is through
ship loads such as in 25000 ,50000, tones and so on, because through this way
the transporting is less cumbersome and one can transport more materials at a
given time.
PRICE
$17.6/KG OR
$8/IB
For more information:
mobile: +2348039721941
contact person: emeaba uche
e-mail: emeabau@yahoo.com
website: www.franchiseminerals.com
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