Metals and Anthophyllite

8. Metals

Iron is the second most abundant metal in the Earth’s crust, behind aluminium. Iron occurs in nature as different compounds. Iron compounds occurring as minerals include siderite as well as iron oxides, such as magnetite, hematite, goethite and limonite. The earliest iron in human use came from iron meteorites. A dagger found from the Egyptian pharaoh Tutankhamun’s burial chamber was made of meteoric iron. Typical iron objects found from the Viking Age and Crusade Period (900–1250) burial grounds are axes, swords, spearheads, arrowheads, horse bits and dam chains. They were likely made of local limonite.

Limonite is an iron ore consisting of iron(III) oxide, with 20–47 per cent iron content. It usually occurs in sand form or coin-like formations at the bottom of lakes or in marshy or boggy areas under the surface peat, also in Finland. Before mining began, limonite was one of the most important sources of iron. To produce iron, limonite is heated in a reducing or blast furnace, resulting in pig iron, also known as crude iron.

WOW: In the Finnish epic The Kalevala, iron is addressed as metal ore sleeping in a marsh, like limonite: “Thou most useful of the metals, thou art sleeping in the marshes, thou art hid in low conditions, where the wolf treads in the swamp-lands, where the bear sleeps in the thickets. Hast thou thought and well considered, what would be thy future station, should I place thee in the furnace, thus to make thee free and useful?” (The rune translated by John Martin Crawford in 1888.)

Red iron oxide
Red iron oxide (Fe2O3·H2O) is an earth pigment. It comes from iron-rich clay, as very fine-grained hematite. The composition varies according to the deposit, the best ones containing up to 95 per cent of iron oxide. Red iron oxide has been used since prehistoric times; for instance, it was used as pigment in rock and cave paintings and in rituals, sprinkled into graves. Red iron oxide was used in the Astuvansalmi rock paintings (circa 3000–2500 BCE) in Ristiina. It is the largest single rock painting site in the Nordics. Red iron oxide is still widely used as red pigment, in Falu red paint. The history of Falu red dates back to the 16th century.

Copper is a reddish-brown, soft and ductile metal, extracted from ores. It was fashioned into weapons, jewellery and tools in the past; currently, it is used particularly in electronics. In prehistoric times, copper was produced in the Middle East, Southeastern Europe, the British Isles and the Ural, to name a few sources. The United States, Zambia, Chile and Peru have large deposits.

Bronze is an alloy comprised of around 12 per cent of tin mixed with copper. Bronze was a significant prehistoric raw material for jewellery and status symbols. Bronze axes and swords made during the Bronze Age (circa 1500–500 BCE) were not very durable in use, so they were likely primarily used as indicators of their wielders’ high social status. During the Iron Age (circa 500 BCE – 1250 CE), bronze was crafted into jewellery. Bronze has been an imported good in Finland, even though bronze casting has been practised locally as well; for instance, some clay pieces of casting moulds for bronze buckles dating back to the 10th century were found in Hylli, Pälkäne.

A soft and malleable noble metal that has been crafted into jewellery for thousands of years. Before World War II, the gold standard was the basis for the international monetary system. Gold content was indicated by carats, pure gold being 24 carats. The Finnish bedrock has gold nearly everywhere, but only in very small quantities. Gold has been mined at the Haveri Mine in Viljakkala and the Orivesi Gold Mine. The largest gold nugget ever weighed in Finland was found in 1935 when Evert Kiviniemi lifted the 392.9-gram lump by shovel from River Luttojoki.

9. Anthophyllite
Anthophyllite is a mineral belonging to the group of amphiboles. It is often found together with other minerals, such as feldspar, quartz and other amphiboles. It forms thin, prismatic or fibrous crystals. Anthophyllite has played an important role in history, as it was used as asbestos fibres for purposes such as construction material. If inhaled, asbestos dust poses a significant risk of cancer. Currently, anthophyllite has no significant uses, as its use in construction materials is prohibited due to its toxicity.