The Olmec colossal heads are at least 17 monumental stone representations of human heads sculpted from large basalt boulders. The heads date from at least before 900 BC and are a distinctive feature of the Olmec civilization of ancient Mesoamerica. All portray mature men with fleshy cheeks, flat noses and slightly crossed eyes; their physical characteristics correspond to a type that is still common among the inhabitants of Tabasco and Veracruz. The boulders were brought from the Sierra de los Tuxtlas, a mountain range in Veracruz. It is thought that the finished monuments represent portraits of powerful individual Olmec rulers. Each is given a distinctive headdress. The heads were variously arranged in lines or groups at major Olmec centres. Dating the monuments remains difficult due to the movement of many from their original context prior to archaeological investigation. Most have been dated to the Early Preclassic period (1500–1000 BC) with some to the Middle Preclassic period (1000–400 BC). (Full article...)
Hübnerite is a mineral consisting of manganese tungsten oxide, with a chemical formula MnWO4. It typically occurs in association with high-temperature hydrothermal vein deposits and altered granites and in alluvial deposits. Hübnerite is the manganese endmember of the wolframite solid solution series, with ferberite (FeWO4) the opposite iron endmember. Color differences between members of the wolframite family are clear and marked, with the color of hübnerite varying from yellowish brown to reddish brown. It was first described in 1865 for an occurrence in the US state of Nevada and was named after the German mining engineer and metallurgist Adolf Hübner. This stacked image, composed of 38 individual photographs, shows red hübnerite crystals with quartz extracted from the Pasto Bueno mine in Pallasca Province, Peru.
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