Gold is one of the rarest elements on Earth and is considered as the most precious of the precious metals. Unlike other metals, it is soft, ductile, resistant to corrosion, almost indestructible and non toxic. Its chemical symbol is Au, that comes from the latin word “Aurum”, which means “shining dawn”. It belongs to the group of the 3d main series of transition elements, of the periodic table. Pure gold has a bright yellow colour and a brightness that are both considered attractive traditionally. Gold and copper are the only “coloured metals”.
Gold can be rarely found in the free form of native gold (Au) in nature. The most usual gold minerals and alloys are presented in Table 1. Of them, most frequently are found the gold tellurides.
Table 1: Gold minerals and alloys (Grammatikopoulos et al. 2005)
| Metal gold (native gold and alloys) | Gold tellurides | ||
| Native gold | Au | Sylvanite | (Au, Ag)2Te4 |
| Electrum | (Au, Ag) | Kostovite | CuAuTe4 |
| Gold alloy | (Au, Ag, Hg) | Calaverite | AuTe2 |
| γ-gold amalgam | (Au, Ag) Hg | Montbrayite | (Au,Sb)2Te3 |
| Weishanite | (Au,Ag)3Hg2 | Krennerite | (Au,Ag)Te2 |
| Auricupride | Cu3Au | Petzite | Ag3AuTe2 |
| Tetra-auricupride | CuAu | Bilibinskite | Au3Cu2PbTe2 |
| Aurostibite | AuSb2 | Muthmannite | (Ag,Au)Te |
| Anyuiinite | Au(Pb,Sb)2 | Bezsmertnovite | Au4Cu(Te,Pb) |
| Maldonite | Au2Bi | Bogdanovite | (Au,Te,Pb)3(Cu,Fe) |
| Zvyagintsevite | (Pd,Pt,Au)3(Pb,Sn) | Buckhornite | AuPb2BiTe2S3 |
| Hunchunite | Au2Pb | ||
| Yuanjiangite | AuSn | ||
| Gold sulphides | Gold selenides | ||
| Nagyagite | Pb5Au(Sb,Bi)Te2S6 | Fischesserite | Ag3AuSe2 |
| Uytenbogaardite | Ag3AuS2 | Petrovskaite | AuAg(S,Se) |
| Criddleite | TIAg2Au3Sb10S10 | Penzhinite | (Ag,Cu)4Au(S,Se)4 |
| Buckhornite | AuPb2BiTe2S3 | ||
| Secondary gold | |||
| Aurantimonate | AuSbO3 | ||
Gold can be also found bound to a mineral matrix in the form of a solid solution (Table 2). Another form of gold is the submicroscopic molecular gold which has a size of 100-5000 Å. The main gold-bearing minerals of this type are presented in Table 3.
Table 2: Gold-bearing minerals, that contain gold in the form of a solid solution (Grammatikopoulos et al. 2005)
| Mineral | Maximum concentration of Au (ppm) |
| Arsenopyrite (FeAsS) | 15,200 |
| Iron pyrite (FeS2) | 13,200 |
| Loellingite (FeAs2) | 275 |
| Luzonite / Enargite (Cu3AsS4) | 418 |
| Marcasite (FeS2) | 1,000 |
| Tennantite (Cu9Fe2+3As4S13) | 40 |
| Tetrahedrite (Cu9Fe2+3Sb4S13) | 72 |
| Chalcopyrite (CuFeS2) | 7.7 |
| Bornite (Cu5FeS4) | <1 |
Table 3: Gold-bearing minerals, that contain colloidal gold (Grammatikopoulos et al. 2005)
| Mineral | Maximum concentration of Au (ppm) |
| Iron pyrite (FeS2) | 2,800 |
| Iron oxides | 1,200 |
| Marcasite (FeS2) | 180 |
| Arsenopyrite (FeAsS) | 20 |
It has been calculated that, from the beginning of known human history to the year 2009, 165,000 tons of gold have been mined in total. The global consumption of gold that is mined can be divided as follows: approximately 50% is used in the construction of jewelry , 40% is used as investment reserves, and 10% is used in industrial applications.
Apart from the widespread monetary and symbolic uses, gold is used in many practical applications, such as dentistry, electronics and other fields.
Its advantages are its high ductility, its resistance to the effects of most of the chemicals, as well as its high electrical conductivity. The applications of gold include, among others, the production of electric cables, of coloured glass, of gold or gilded dinner sets and, lately, the construction of CD-ROMs and photovoltaic cells.
The Greek gold
Remarkable gold concentrations have been found in Greece, in the wider area of Stratoni in Chalkidiki, in Sappes and Perama in Western Thrace, in Kilkis and in Milos. Smaller concentrations can be found in Pangeo, Angistro of Serres, Lesbos, Lemnos and Chios.
Bloomberg has written in 2012 that “Greece can overcome Finland as the number one gold producing country in Europe in the next four years”. This was the case because it seemed at the time that the competent Greek Authorities have begun to “unblock” agreements that remained “frozen” for more than a decade, due to bureaucracy and environmental regulations.
Greece was the largest bauxite producing country in Europe and the number one perlite supplying country in the world in 2010, according to the U.S. Geological Survey. Gold is, for the time being, the only metal that has been included in the fast track programmes in 2012, by the previous government. If all went well, the four mines of Eldorado Gold Corp and of Glory Resources Ltd could turn Greece into the largest gold producing country in Europe by 2016. Gold mining began to “accelerate” from the day that Greece began implementing the fast-track programme regarding the approval of projects. The Canadian and the Australian company have declared at the time, that their projects could add approximately 425,000 ounces of gold by 2016, with a net value of over 700 million dollars, to the 16,000 ounces that Greece produced in 2011.
Environmental organizations, the local opposition and the electoral promises and declarations of the current government that won the elections of January 2015, consist the biggest obstacle regarding gold mining in Greece.