Old Copper Mandrils

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Copper Artifacts

Old Copper Mandrils

by E.J.Neiburger, Waukegan, Illinios

Originally Published in the Central States Archaeological Journal, Vol.55, No.2, pg.80

A mandril is an object which is used as a form to fabricate a wrought item. For ex­ample, a solid bar of steel can be used as a mandril (form) onto which a copper plate is hammered and bent into a hollow tube shape. Mandrils are very helpful because they stan­dardize manufacture. Items made on the same mandril will be similar in size and shape. In our modern society, mandrils are a common tool for manufacture.

The Old Copper Culture of the upper Mid­west United States spanned from 8,000 years ago to present times. Early Indian metal smiths used naturally occurring float copper to fashion a wide variety of pure copper tools, weapons and ornaments. Thousands of these Old Copper implements have been found in Wisconsin, Michigan, Ohio and adjoining states.

Recent discoveries of Old Copper caches in Wisconsin have contained numerous coni­cal copper spear points and the mandrils used to manufacture (shape) them.(Figures 1a-11)

The Artifacts

One of the most frequently discovered Old Copper implements is the conical point. This object type is easily made, simple in design and quite useful as a weapon tip and pierc­ing tool ( e.g. an awl-like instrument used to make holes in hides, wood, etc.)(Figures 1 a-11). They look like miniature copper, ice cream cones.

Most conicals range in size from 1 cm to 5cm in length and from 0.5cm to 2.5cm in diameter at the widest (open) end (Figures 1 a, lb). They have two ends: the "pointed" end and the "open" end. They all have a sharp pointed tip on one end and a wide, open end which would receive a wood, bone or other type of handle (shaft) material. Many of the conicals found at individual sites are of simi­lar size and shape. They seem to have an open end with a standard sized opening. Most of the conicals, unless crushed, have near-perfectly round (circular) open ends. This is quite dif­ficult to accomplish free hand unless one were to use a mandril as a template or guide.

The mandrils are solid "rods" of copper, carefully hammered, ground and shaped to form a tapered end.(Figures 2-11). They ranged from 10cm to 20cm in length. Most have differing tapers on each end thus serv­ing a dual purpose of making two differ­ent sized conicals (multi-purpose tool). The mandrils were repeatedly pounded, and as a result, are metallurgically strain hardened. They hold their shape much better than lightly beaten copper. Repeated hammering causes increased crystallization of the microscopic grain structure of the copper. They become hardened, brittle and corrosion resistant. This is seen at sites where mandrils are found in a less corroded condition than the other ac­companying copper artifacts . This is unique since all the copper implements at the site had similar environmental assaults upon their metal structure (Figures 2,3).


Figure l a
Conical copper points from Vilas Co.,Wisconsin.


Figure 1 b
Six varieties of conical points.


Figure 2
Copper collection from a single Wisconsin site.
Note the mandril with a conical point, preform
knives and a large number of hammered copper
nuggets probably used as raw materials or trade
currency (money).

The copper metal smith would take a lump of copper, hammer it into a triangular shaped, flat plate and then pound it around the mandril until it assumed a conical, "ice cream cone" shape (Figures la-11). At times the cone would be completely closed with both edges of the copper meeting each other.(Figures la, lb) Other times the cone edges would be left open to various degrees (Figures 7-11). If the metal was sufficiently thick, loss of strength would not be an issue whether the cone edges met or not. The copper smith would then sharpen the metal tip, fabricate a shaft (wood has oc­casionally been found inside conical copper points) and the weapon would be ready for use.

The Discovery

Twenty-two Old Copper producing sites in Vilas County, Wisconsin were explored us­ing metal detectors to locate and recover near-surface copper artifacts. Two of these sites (2) were under lakes and streams. Of the 22 sites, 5 possessed one mandril, one site possessed two mandrils and 16 sites did not have any identifiable mandrils.(Figure 5). A total of 250 conical copper points were found at the 22 sites.

One site had a conical point permanently stuck to a mandril. It would not come off. This illustrates a particular hazard of this form of manufacture. In order to effectively manufacture conical copper points, one must not hammer so excessively as to permanently bind the point (mechanically) to the mandril.

The Fit

The seven mandrils easily fit into many of the conical points from the same respective site.(Figures 2-9) The fit was quite tight with very little space seen when the conical point was firmly pushed on to the mandril. Figures 10 and 11 show the equal edge spacing of points partially pushed onto their respective mandrils. The conical points were made on their respective mandrils.

The fit between the points and the man­drils, in most of the cases, were near-perfect presenting a question: why would the manu­facturing tools (e.g. mandril) accompany the finished product? In most industries, the tools are kept separate from the completed product. One does not get the lathe with the machined part or the hammer with the forging. Why do we see so many mandrils with the caches of Old Copper implements?

Roving Workshop Theory

Many archaeological discoveries expose large groups (caches) of stone points in vari­ous stages of manufacture. Preforms are the most common and entail numerous unfinished implements, all showing the same level of production. These are often found scattered at minor sites and old camps as well as at long term habitation locals. Often the tools of manufacture accompany the preforms. These may include antler horns, striking stones, bea­ver teeth, etc. which are traditionally used in the finer aspects of manufacture (e.g. edge or notch construction). Numerous Old Copper sites show similar situations involving cop­per where nuggets of float copper are found grouped with a variety of copper performs and finished implements (Figures 2 & 3).

It appears that the ancient natives worked on the implements as they traveled and, in all probability, traded them. An individual or group of individuals would secure a batch of stone or copper preforms from a commu­nity which specialized in mining/collecting the raw product and then partially refined it (making performs). They would transport the performs to "market" which often would require long journeys. During the trip, when not traveling (e.g. night, bad weather), the merchants would work on the preforms, refin­ing them into finished products. This would consume significant amounts of otherwise useless "downtime" and enhance the value of the product when it finally reached the intend­ed market be it middlemen or the consumer. These seem to be single type operations where only stone or only copper is found; seldom both. These traders were specialists.


Figure 3
Copper collection from another Wisconsin site
showing a short mandril with a close-fitting conical
point. Fish hooks, awls, knives and hammered cop-
per nuggets were also found at the site.

The discovery of tools like mandrils and preforms or finished implements (stone or copper) is compelling evidence for this prac­tice. Occasionally caches of these implements would be buried or otherwise lost and later discovered by the archaeologist. I believe that these collections of copper mandrils, fit­ted conical points and other Old Copper metal artifacts (along with collections of slightly hammered copper nuggets) are diagnostic for traveling workshops as described above.


Approximately one third of the 22 Old Cop­per sites examined show close-fit evidence of the use of metal mandrils in the manufacture of conical copper points. These tools and prod­ucts are found in caches exhibiting partially worked "preforms" which suggests the exis­tence of an archaic period trade system where bulk natural copper was refined into finished products during transportation to market.



I would like to thank Andent, Inc., Alan Stone-metallurgist and Steve Livermore-ar­chaeologist for their invaluable assistance.


"Used by Permission of the Author"
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