Allchar deposit
Encyclopedia
Allchar deposit is a low-temperature hydrothermal gold
–arsenic
–antimony
–thallium
deposit
in southern Macedonia
. For some time, the thallium-rich part of the deposit was mined. The Crven Dol mine yielded thallium
and the ore body still holds estimated amount of 500 t of thallium. The mineral lorandite
from this ore deposit is being used to determine the solar neutrino
flux.
, similar to those found in the Carlin Unconformity
, Nevada
.
, orpiment
, As-bearing pyrite
and marcasite
The deposit was mined extensively between 1880 and 1908. Antimony, arsenic and thallium were produced during that period.
, orpiment and realgar are the main minerals forming the ore. Lorandite – a thallium arsenic sulfosalt minerals
with formula TlAsS2 – is the main thallium mineral in the deposit. Several other thallium mineral have been discovered in the mine over the years, for example, jankovićite (Tl5Sb9(As,Sb)4S22, fangite (Tl3AsS4) and bernardite (TI(Sb,As)5S5).
flux. This mineral contains large amounts of thallium-205 which undergoes a neutrino capturing reaction and yields lead-205 in the process. The 205Tl(νe,e-)205 process has a relatively low threshold energy of 52 keV
and thus relatively high efficiency. With the age of the deposit of 4.5 to 4.2 million years, the solar neutrino flux can be estimated over the last 4 million years provided it is possible to determine the amount of lead-205 in a lorandite sample. This reaction can be induced not only by neutrino but other high energy cosmic particles, which all have different penetration depth in the crust. Therefore, a large volume of data is being accumulated during 2008–2010 from different depths of the deposit to produce reliable data.
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
–arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
–antimony
Antimony
Antimony is a toxic chemical element with the symbol Sb and an atomic number of 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite...
–thallium
Thallium
Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy...
deposit
Deposition (geology)
Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of...
in southern Macedonia
Republic of Macedonia
Macedonia , officially the Republic of Macedonia , is a country located in the central Balkan peninsula in Southeast Europe. It is one of the successor states of the former Yugoslavia, from which it declared independence in 1991...
. For some time, the thallium-rich part of the deposit was mined. The Crven Dol mine yielded thallium
Thallium
Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy...
and the ore body still holds estimated amount of 500 t of thallium. The mineral lorandite
Lorandite
Lorandite is a thallium arsenic sulfosalt with the chemical formula: TlAsS2. Though rare, it is the most common thallium-bearing mineral. Lorandite occurs in low-temperature hydrothermal associations and in gold and mercury ore deposits...
from this ore deposit is being used to determine the solar neutrino
Solar neutrino
Electron neutrinos are produced in the Sun as a product of nuclear fusion. By far the largest fraction of neutrinos passing through the Earth are Solar neutrinos....
flux.
Geology
The deposit is a Carlin–type gold depositCarlin–type gold deposit
Carlin–type gold deposits are sediment-hosted disseminated gold deposits. These deposits are characterized by invisible gold in pyrite and arsenopyrite...
, similar to those found in the Carlin Unconformity
Carlin Unconformity
The Carlin Unconformity or Carlin Trend is a geologic feature in northeastern Nevada which represents a period of erosion or non-deposition likely associated with a collision between a tectonic crustal block called a terrane and the North American Plate. The collision occurred during the...
, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
.
Mining
Crven Dol mine operated in the antimony-poor and arsenic and thallium rich layer of the orebody. The minerals making most of the orebody are realgarRealgar
Realgar, α-As4S4, is an arsenic sulfide mineral, also known as "ruby sulphur" or "ruby of arsenic". It is a soft, sectile mineral occurring in monoclinic crystals, or in granular, compact, or powdery form, often in association with the related mineral, orpiment . It is orange-red in colour, melts...
, orpiment
Orpiment
Orpiment, As2S3, is a common monoclinic arsenic sulfide mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.46. It melts at 300 °C to 325 °C...
, As-bearing pyrite
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
and marcasite
Marcasite
The mineral marcasite, sometimes called white iron pyrite, is iron sulfide with orthorhombic crystal structure. It is physically and crystallographically distinct from pyrite, which is iron sulfide with cubic crystal structure. Both structures do have in common that they contain the disulfide...
The deposit was mined extensively between 1880 and 1908. Antimony, arsenic and thallium were produced during that period.
Minerals
Pyrite stibniteStibnite
Stibnite, sometimes called antimonite, is a sulfide mineral with the formula Sb2S3. This soft grey material crystallizes in an orthorhombic space group. It is the most important source for the metalloid antimony...
, orpiment and realgar are the main minerals forming the ore. Lorandite – a thallium arsenic sulfosalt minerals
Sulfosalt minerals
Sulfosalt minerals are those complex sulfide minerals with the general formula: AmBnSp; where A represents a metal such as copper, lead, silver, iron and rarely mercury, zinc, vanadium; B usually represents semi-metal such as arsenic, antimony, bismuth and rarely germanium, or metals like tin and...
with formula TlAsS2 – is the main thallium mineral in the deposit. Several other thallium mineral have been discovered in the mine over the years, for example, jankovićite (Tl5Sb9(As,Sb)4S22, fangite (Tl3AsS4) and bernardite (TI(Sb,As)5S5).
LOREX
LORandite EXperiment (LOREX) is using lorandite from the ore deposit to determine the solar neutrinoSolar neutrino
Electron neutrinos are produced in the Sun as a product of nuclear fusion. By far the largest fraction of neutrinos passing through the Earth are Solar neutrinos....
flux. This mineral contains large amounts of thallium-205 which undergoes a neutrino capturing reaction and yields lead-205 in the process. The 205Tl(νe,e-)205 process has a relatively low threshold energy of 52 keV
Kev
Kev can refer to:*Kev Hawkins, a fictional character.*Kevin, a given name occasionally shortened to "Kev".*Kiloelectronvolt, a unit of energy who symbol is "KeV".* Krefelder Eislauf-VereinKEV can refer to:...
and thus relatively high efficiency. With the age of the deposit of 4.5 to 4.2 million years, the solar neutrino flux can be estimated over the last 4 million years provided it is possible to determine the amount of lead-205 in a lorandite sample. This reaction can be induced not only by neutrino but other high energy cosmic particles, which all have different penetration depth in the crust. Therefore, a large volume of data is being accumulated during 2008–2010 from different depths of the deposit to produce reliable data.