STONE SLAB FURNACES

IN THE FINNISH IRON AGE

BA Joni Karjalainen

THE FINNISH IRON AGE AND IRON

• The Iron Age ranges from 500 BC to 1050/1150 AD• Varies between the regions• Ends much later than in other parts of main Europe

• Iron probably came from the East• Contacts already in the Bronze Age• Similar furnace types from the Republic of Karelia

• Changed livelihoods and beliefs• Equalized the society as iron ore is easier to obtain• Especially in Finland it can be found from lakes and bogs

LAKE IRON ORE (LIMONITE)

TRACES OF IRON SMELTING

• There is very little evidence of furnaces in the Finnish archaeological record• But there is slag• Problematic due to difficulties in dating and identification as

smelting slag

• Few possible furnace bottoms, but they haven’t been dated properly

• Either they are not recognised or there is so few of them

• Interestingly all definite furnaces are found in Eastern or Northern Finland• Considered to be the periphery of the Iron Age

• Only stone furnaces survive

STONE SLAB FURNACES

• Built from big slate stone slabs• Size varies between furnaces surprisingly little

• Partly underground• Dating in Finland ranges from 400 BC to 600 AD• They had to work, if they were used for such a long time• Most fall to the Early Iron Age, 500-300 BC

• There are five definite ”box” furnaces in Finland and one from northern Sweden (Jernbacken), but the biggest number of them comes from the Republic of Karelia, Russia

STONE SLAB FURNACES

Riitakanranta (Rovaniemi) furnace in situ. Photo: Hannu Kotivuori, Lapin Maakuntamuseo

Stone slab furnacesLocation Dimensions Slag pit Clay inlayKitulansuo D, Ristiina 70 x 50 x 20 cm No YesKotijänkä, Rovaniemi 40 x 50 x 25 cm Yes NoRiitakanranta, Rovaniemi 65 x 32 x 25 cm Yes No

Nastola, Kilpisaari77-85 x 43 x c. 23 cm No ?

Äkälänniemi, Kajaani 70 x 40 x 25 cm Yes Yes

RIITAKANRANTA, ROVANIEMI

Drawing by Hannu Kotivuori, 1995.Excavation report, Rovaniemi 474 a-c, Korkalo, Riitakanranta

EXPERIMENTATION

• Not really researched through experimental archaeology• Few tests or try outs

• Several interesting questions• Position of tuyere(s)?• Wind powered or bellows?• At least two of the furnaces suggest the latter

• Single charge or continuous smelt?• If continuous, how was it refilled?

TODAY’S PRE-EXPERIMENT

• First time using this type of furnace• Setting:• Measurements 60 x 40 x 25 cm• Tuyere and bellows in the middle of a long side• Clay lining to protect the stones• Big slate stone as a lid• Roasted lake iron ore

• Short test with charcoal on Thursday

FURNACE