archaeometallurgy

The glossary lists terms related to metallurgy. German translations are given where necessary. These red links a will get you to the German glossary and explain them in German. If you use the glossary for your work I’d appreciate if you would cite this page or else provide a link to this glossary.

A B C D E F G H I K L M N O P Q R S T U V W Z

A

aes brundisium

latin name for →Bronze. Literally ore from brundisium, the important port, where shipments of this material arrived. Ore is often used to describe metal. This was done until the 19th century.

aes corinthium

Corinthian ore is a copper →alloy whose surface can be treated to a dark-brown to aubergine colour. The main components are Copper (Cu), Silver (Ag) and Gold (Au).

aes cuprum

latin for →Copper

Alloy →(die) Legierung

An alloy is a solution of two or more chemical elements, of which one at least is a metal. Good examples are →bronze a mixture of →Copper and Tin, or Carbon-steel, an alloy of →Carbon and iron.

Azurite →(der) Azurit, (die) Kupferlasur

Etymology: lat. azzurum for blue originating from arab. lazaward = blue Chemical formula: Cu₃(C0₃)₂(OH)₂ Mohs scale: 4 Density: 3,9 Environment: Azurite is a secondary mineral of the oxidized zone of an ore deposit. More specific details can be found in the mineralogy database

B

Black copper →(das) Schwarzkupfer

Product of a smelting process of sulfidic ores known as→matte smelting. Black copper has a copper content pf 90% and has to be refined before it can be used for further metallurgical processes such as casting.

Blister copper →(das) Schwarzkupfer

see →black copper

Brass →(das) Messing, (der) Gelbguss

An →alloy of →Copper and →Zinc (Zn). The discovery that Zinc and Copper are the components of brass was only discovered in 1657 by Johann Rudolph Glauber (1604 – 1670). Before that brass was produced by the cementation process. Copper, finely ground →calamine, a zinc ore and charcoal were heated in a crucible to approximatey a 1000°C. The forming Zinc gas diffused into the Copper and formed the alloy in a solid state process. Then copper-alloy might have eventually liquified in the crucible. The chemical process is as follows:ZnCO₃ → ZnO + CO₂ ZnO + C → Zn + CO Alchemists did NOT understand that an alloy was produced. They regarded this as the colouring of copper by the arts; probably because ZnO (Zinc oxide) is a white substance and it was not acknowledged as a metal ore.

Bronze

Etymology: lat. aes brundisium: ore from Brindisi after the ancient port of Brundisium. We think the alloy might have been shipped to this port and then distributed through the Roman empire. The →alloy consists of →copper (Cu) and →tin (Sn). With 10% tin contents the alloy is liquid above 1020°C.

Bronze age →(die) Bronzezeit

Term was introduced by Christian Jürgensen Thomson in 1836 and divided the prehistory of mankind into stone age, bronze age, and iron age. In central Europe the Bronze Age starts roughly at 2300 BC and ends around 800 BC.

C

calamine →(der) Galmei

Old fashioned name for the zinc ores zinc spar (Smithsonite, zinc carbonate) ZnC0₃ and Hemimorphite (zinc silicate) Zn₄Si₂O₇(OH)₂ x H₂O. The name was used for both minerals. Zinc spar produces zinc oxide ZnO and Carbondioxide CO₂ when annealed.

Carbon-steel →(der) Kohlenstoff-Stahl

An alloy of Iron (Fe) and Carbon (C). Up to a Carbon content of 2.06% it is called Carbon-steel. Above we refer to it as →cast iron.

Cassiterite →(der) Kassiterit, (der) Zinnstein

Etymology: From phoenician “Cassiterid”, which described the English and Irish islands. Another phoenicin word for Tin-land is B’ratan’ of which Aristotele developped the word “Britannic”. Chemical formula: SnO₂ Crystal system: tetragonal (vierkantig) Mohs scale: 6 – 7 Density (g/cm³): 6,8 – 7 / average = 6,9 Notes: Most important Tin-ore More specific details can be found in the mineral database

Cast iron →(das) Gusseisen, (der) Grauguss

Cast iron or grey cast iron is an alloy of Iron (Fe) and carbon (C), just like carbon-steel. The major difference is the proportion of carbon. Cast iron has more than 2.06% carbon. The →eutectic →alloy has a carbon contents of 4.3%.

Cementation →(die) Zementation

Cementation is a metallurgical solid state process. In a heated environment one metal stays solid, the other substance/metal is gaseous and is absorbed by the solid substance, thus forming an alloy. There are a few example for this process, e.g. the production of →brass or Wootz-/crucible-steel.

Chalcocite → (der) Chalkosin, (der)Kupferglanz

Etymology: gr. chalkos – Copper, Bronze Chemical formula: Cu₂S Crystal system: monoclinic – prismatic Mohs scale 2,5 – 3 Density: 5,8 Environment: Secondary mineral near or in oxidized copper sulfide ore deposits. More specific details can be found in the mineralogy database

Chalcopyrite (der) Chalkopyrit, (der) Kupferkies

Etymology: gr. chalkos = Copper and gr. pyr = Fire. Chemical formula: CuFeS₂ Crystal system: tetragonal Mohs scale: 3,5 Density: 4,1 – 4,3 Environment: Abundant in sulfide ore deposits. Chalcopyrite is the most important Copper ores, with copper contents up to 34,5%. More specific details can be found in the mineral database

cope →(der) Oberkasten

Upper part of the →flask

Covellite →(der) Covellin, (der) Kupferindig

Etymology: in honour of the italian Mineralogist N. Covelli, who did the first chemical analysis. Chemical formula: CuS Crystal system: hexagonal Mohs scale: 1,5 – 2 Density: 4,6 Environment: Mostly a secondary mineral of sulfide ore bodies in the oxidation zone. More specific details can be found in the mineral database

Copper →(das) Kupfer

Etymology: lat. aes cuprum: Ore of Cyprus, origin: gr.: κϒψρος ‘kypros’: name of the island Cyprus, were copper ores were mined since prehistoric times. Copper (Cu) has a melting point of 1083,4°C.

Crucible →(der) Tiegel

Crucibles are the containers in which metals are molten. They are often made of clay material. These are usually refractory enough to withstand the temperature shocks during melting and subsequent casting.

Crucible steel →(der) Tiegelstahl

Wootz-steel is a steel which is formed in a process called cemetation. This steel was produced as early as the 6th century AD in India. Another important centre for the production of crucible steel was Uzbekistan in the 10th century. Iron and carbon-rich material (e.g. plants, charcoal, etc) were placed in a →crucible and heated for a prolonged period of time. The carbon would form Carbonmonoxide (CO) and enrich the carbon content of the iron, thus forming the steel alloy.

Cu

see →Copper.

Cupellation → (die) Kupellation, (die) Treibarbeit, (das) Abtreiben

A process for the production of silver, by enrichment of argentiferous (silver-bearing) lead (Pb). Oxygen is blown onto a molten silver-bearing lead “alloy”. The base metal lead is oxidized, the noble metal silver stays as rest = regulus in the cupelle. The lead oxide (Litharge) is absorbed by the cupelle. The chemical process can be described as follows:Pb _{and metals} + O₂ → PbO _{and base metal oxides} + Pb _{and noble metals} The process is discountinued, when all lead is oxidized.

Cupelle → (die) Kupelle, (die) Kapelle (old fashioned)

Cupelles are containers for the metal in the →cupellation process. In contrast to →crucibles cupelles consist of compressed bone-, or plant-ash or magnesia (magnesium oxide). This is necessary for the molten →litharge (lead oxide) has to be absorbed by the porous cupelle.

Cuprite →(der) Cuprit, (das) Rotkupfererz

Etymology: lat. cuprum = Copper Chemical formula: CU₂O Crystal system: isometric – hexoctahedral Mohs scale: 3,5 – 4 Density: 6, 1 Environment: Oxidation zone of copper ore bodies More specific details can be found in the mineral database

D

deposit →(die) Lagerstätte

The source of →ores are called deposits. Ores can occur in deposits or →placer deposits

Die →(die) Kokille

Dies are →permanent moulds consisting of metal, usually steel, but sometimes also cast iron, or for prehistoric times of copper alloy.

downsprue →(der) Eingusstrichter

The casting funnel or slip cap. The first, usually vertical part of the →gating system in which metal is poured to reach the mould cavity. See also →sprue, →vent, →runners

drag →(der) Unterkasten

Lower part of the →flask

E

Eutectic →(das) Eutektikum

Etymology: griech. ευ ‘eu’: good and τεκτειν ‘tektein’: build. An alloy is eutectic when the proportions of the components are such that the alloy is above a given →melting point liquid (→Liquidus temperature) and below the same temperature (solidus temperature) completely solid. The eutectic is reached when both points fall together, the eutectic point. This is usually the lowest melting point of any proportion of components. Since this alloy will solidify almost instantly at a given temperature a fine grained and uniform microstructure is produced.

F

Feeder →(der) Speiser, (der) Steiger

Feeders or risers are reservoirs of molten metal in the mould that are used to feed the mould with metal during solidification. As metal shrinks when it solidifies, the risers have to be applied in way the solidify last. This is an industrial concept where huge amounts of metal are poured, or great wall thicknesses have to be realised. It is rarely applied in prehistoric or art casting.

Flask →(der) Kasten

Flasks are frames that hold the molding sand of sand moulds. They are usually made from steel, aluminium or bronze. They consist of two halves called →cope and →drag.

Flowability →(die) Bildsamkeit

also plasticity. The property of moulding materials to flow around the model or pattern. Flowability is responsible for good surface reproduction.

Galena →(der) Bleiglanz, (der) Galenit

Lead sulfide (PbS); important lead ore, called argentiferous if Silver is built into the crystal structure. Therefore can also be an important Silver ore.

Gangue →(die) Gangart

Minaerals and rock that are intergrown with →ores and do not contain any metal you can smelt.

Gate →(der) Anschnitt

The specific part where the sprues connect with the mould cavity. The term is also used in a more general way to describe the →gating system.

Gating system →(das) Anschnittsystem

The system of →downsprue, →sprues, →vents, →runners, →risers and →feeders, which allow for the metal to reach the cavity.

Gossan →(der) Eiserne Hut

The upper part of an ore mineralisation, which formed as a result of supergene sulfide ore alteration. Weakly acid surface water perlaocates trhrough the mineralisation, therby bringing copper and other suulfide minerals into solution. The insoluble iron hydroxides, such as limonite, remain at the top and form the gossan or iron cap. Read more in this post on the gossan on en.archaeometallurgy.de

Grey cast iron →(der) Grauguss

see →Cast iron

Grog; grog, to →(die) Magerung →(die) Schamotte

Ground pot sherds, ceramics, high fired ceramics, which are used to influence the properties of clay, e.g. refractoriness or shrinking.

H

I

Iron cap  →(der) Eiserne Hut

→gossan

J

K

L

Liquidus temperature →(die) Liquidustemperatur

Litharge →(die) Bleiglätte

Lead oxide (PbO). Amongst others a by-product of Silver enrichment/Silver production (→cupellation)

The liquidus temperature marks the point when all components of an →alloy are present in a liquid state.

Loam →(der) Lehm

Loam is a naturally occuring soil consisting of the three mineral size fractions →clay, →silt and →sand.

lycopodium →(das) Lykopodium

Parting agent in sand moulding. It prevents green sand from sticking to the pattern or from cope and drag to stick together. In the olden days lycopodium bisdepuratum was used for this purpose. Today it is made from ground resins.

M

Malachite →(der) Malachit

Chemical formula: Cu₂(C0₃)(OH)₂ Crystal system: monoclinic Mohs scale: 4 Density (g/cm³): 4 Environment: Secondary mineral in copper deposits; very common. Important depostis aer in Katanga, Kongo. Usage: Malachite was used as pigment in antiquity. It is an important indicator for copper deposits. More specific details can be found in the mineralogy database.

Marcasite →(der) Markasit

Chemical formula: FeS₂ Crystal system: orthorhombic – dipyramidal Colour: bronze, lightbrown yellow, tin-white, greenish black Mohs sclae: 6 – 6,5 Density (g/cm³): 4,89 More specific details can be found in the mineralogy database.

Matte →(der) Stein

A typical range of products of the smelting process of sulfidic ores if →roasting is an integral part of the →smelting process. Alternating roasting and smelting under reducing atmosphere results in an enrichment of the metal component in the ore. The English terminology is less exact than the German one which differentiates several matte phases with increasing metal contents, until the preliminary endproduct, the black copper or blister copper is produced. Blister copper has a copper contents of 90%. (BACHMANN 2000, S. 133f)

Minerals →(das) Mineral

Minerals occur naturally and are defined by their chemical compound, their chrystal structure and their mechanical and physical properties.

Miner’s tools →(das) Gezähe

Tools used by miners to mine the ore.

Model →(das) Modell

A model resembles in shape and dimensions exactly the object you would like to cast in metal. Depending on the moulding process you will either create a lost model or a permanent pattern (for sand casting). Models for the lost-wax process are obviously made from bee’s wax, or nowadays from microccrystalline wax.

Moulding loam →(der) Formlehm

Moulding loam is the loam you prepare for the use of loam moulds. It is compostion of clay, sand and grog. If it is prepared carefully it will have all the necessary properties moulding materials must exhibit, such as →refractoriness, →permeability and ruggedness.

N

native →gediegen

Metals that are found in there elemental form are called native metals. Native metals may be found where an ore body crops out to the surface. In the regions below the →gossan, in so called the oxidation zone, native metals may occur.

Naturally bonded moulding sand →(der) Naturformsand

This sand consists mainly of →quartz (SiO₂) in the form of fine-sand (0.063mm – 0.2mm) bonded by naturally occurring clay. For moulding purposes the proportion of clay should range between 8-15% clay.

O

Ore →(das) Erz

Ores are →Minerals of which metal is produced by employing the process of →smelting. Two main groups of ore exist: oxidic and sulfidic ores. Oxidic ores are in general of limited availability, are free of gangue and can esily be smelted. Sulfidic ores (compounds wih Sulfur (S)) are more abundant, are usually required to undergo a preceding →roasting process and are often intergrown with gangue. It becomes immediately apparent that these are by far more challenging to smelt. Ore is an economic term, and another prerequisite is that is has to be economically worthwile to smelt these in order to produce metal. For →Copper there are few economicall important ores: →Chalcopyrite, →Chalkocite, →Covellite and →Cuprite. →Cassiterite is the most important ore for the production of →Tin.

Oxidation →(die) Oxidation

Chemical reaction where in the simplest case Oxygen (O₂) is accepted. During oxidation the substance to be oxidised (electron donator) gives off electrons to the oxydiser (electron acceptor). The oxydiser is at the same reduced (→Reduction). An oxidation is always associated with a reduction and both are parts of the redox reaction.

P

Permanent mould →(die) Dauerform

Permanent moulds are re-usable moulds; they are opened rather than destroyed to retrive the cast. They can consist of steel, cast-iron, bronze, sandstone or soapstone.

Permeability →(die) Gasdurchlässigkeit

Permeability is an important property of the moulding material and describes the degree of gas flow through the moulding material. It facilitates the filling of the mould cavity. Although this does usually subsitute for the application of →vents.

Placer deposit →(die) Seife

Placers or placer deposits are deposits of secondary origin. Through wheathering and mechanical (fluvial) transportation ores can be congregated and enriched. Concentrations of ores are usually higher than in the original rocks. Typical ores of placers would be those of tin, gold, platinum, niobium, tantalum, titanium, zirconium. Diamonds are also to be found in placers. (EDWARDS, R. & K. ATKINSON 1986, S.175ff).

Potassium →(das) Kalium

Chemical element. Chemical formula K for Kalium (lat.) from al qalja = plant ash. Interestingly the word potassium has the same meaning, since it the latinised form of pot ash. Potassium is the main component of pot ash (K₂CO₃). Since this potssium salt is present plant ash and furthermore is water soluble, it was enriched in water and the water subsequently evaporated in clay pots. Hence pot ash. Find more information on sodium on Wikipedia.

Q

Quartz → (der) Quarz

SiO₂, abundant chemical mineral, as opposed to →silica, the chemical compound. Refractory material which liquifies at 1650±75°C. Main component of many moulding materials.

Quenching →(das) Abschrecken

Rapid cooling of red hot metal to room temperature or below, for example by immersing in water or oil.

R

Reduction →(die) Reduktion

Chemical reaction where in the simplest case Oxygen (O₂) is given off. For →smelting it is important that electrons are accepted. See also →oxidation.

Refractoriness →(die) Feuerfestigkeit

Riser →(der) Steiger, (der) Speiser

see →feeder

Roasting →(das) Rösten, (der) Röstvorgang

Roasting is a step in the primary production of metals from →ores. It is a step preceding the →smelting of the ore. It →oxidises compounds that could otherwise not be smelted in reducing conditions. This step is necessary for almost all sulfidic ores.

S

Sand →(der) Sand

Mineral size fraction of the soil between 0,063mm und 2,0mm. Sand is next to →silt and →clay a constituent of →loam.

chamotte →(die) Schamotte

Chamotte are highly fired and ground clays, which are mainly used as →temper or →grog.

Silt →(der) Schluff

Mineral size fraction of the soil between 0,063mm und 2,0mm. Sand is next to →clay and →Sand a constituent of →loam.

Shrink hole →(der) Lunker, (der) Gusslunker

Casting defect, due to the solidification of metal in layers from the outside to the inside of the mould cavity. As metal shrinks when solidifying, this creates a lack of metal. In large diameters shrink holes appear as funnel shaped recesses with a rough surface. The correct apllication of →risers in the gating system will prevent this kind of casting flaw.

Silica →(die) Kieselsäre

Silicon dioxide SiO₂; chemical compound of Silicon (Si) and Oxygen (O₂).

Smelting →(die) Verhüttung

Primary production of metals. Ores are smelted to metals. Simple ores, such as oxidic ores can be →reduced to metal in a single smelting process. More complex ores, such as sulfidic ores have to be →roasted, i.e. compounds that cannot be directly reduced have to be oxidised first, before the ore can be reduced to metal. Depending on what ore is smelted, it has sometimes to be →beneficiated as well, which is the separation of ore and gangue.

Smithsonite

See →zinc spar

Sn

see →Tin

Sodium →(das) Natrium

Chemical element. Chemical formula Na. From egypt. netjer = natron arab. natrun = (sodium bicarbonate or sodium hyrogen carbonate) NaHCO₃. Find more information on sodium on Wikipedia.

Solidus temperature →(die) Solidustemperatur

Denomoinates the temperature at which an alloy is completely solid. In case of a 10% Tin alloy this is 798°C. Above this temperature there are two phases present in the alloy: a liquid and a solid one. The alloy is in the mushy stage. Once the →Liquidus temperature is exceeded the alloy is completely liquid.

T

Tempering 1. →(das) Anlassen 2. →(die) Magerung

1. Reheating of metal object, i.e. after hardening to tempeartures up to 732°C. Tempering releases internal strain and promotes toughness as opposed to brittleness resulting from hardening. →Temper colours are an important indicator for the assessment of the temperature. 2. Step in preparing clay for the use for pottery or ceramics, such as pots, crucibles, moulds, etc. Usually ingredients other than clay, e.g. →grog, sand, chaff, animal hair, plant fiber, etc.

Temper colour →(die) Anlassfarbe

Temper colours originate from →oxidation of the surface of clean metals when heated. Distinct colours represent distict temperature intervals; e.g. carbon-steel has a cornflower-blue colour at 300°C. A standard temper colour chart can only be applied to carbon-steels.

tin →(das) Zinn

Tin is a metal. Tin is an element. Tin possesses a melting point of 232 °C and a boiling point of 2270 °C. Despite the high boiling point profound tin losses may occur during melting a coppper tin alloy. This is due to preferential oxidation of tin and not due to “boiling off” tin, because tin is the baser metal in this alloy. Silevery, shiny and soft metal. Charactzeristic is the creaking of pure tin when it is bent. Up to modern times the metals tin, lead and zinc have not been identified as different metals. This was only possible with the advent of chemistry as a science with the beginning of the 19th century.

U

V

Vent →(der) Luftkanal, (die) Entlüftung

Vents connect the mould cavity with the outside, but contrary to the gates, they are for the gases and air which, otherwise would be trapped with thae cavity. Sometimes with large moulds these gases can be ignited, thus creating a negative pressure in the mould. Generally speaking it is enough if the vents are attached to the highest points of the cavity.

W

Z

Zinc →(das) Zink

Zn. Melting Point 419,5 °C; Boiling Point 907 °C. It was only in the 17th century discovered that zinc is a metal. William Champion patented his method of zinc production by distillation in 1738. Since zinc’s boiling point is so low it was previously impossible to produce zinc-metal with the known smelting processes. It would have rather evaporated than liquified.

Zinc spar →(der) Zinkspat

Zinc carbonate ZnCO₃. Important zinc ore. Also known as Smithsonite.