Arrastras are quite common throughout the western U.S. from 1849 through
1930s, as Ron notes. They were initially introduced by miners of
Mediterranean extraction (Mexican, Chilean, Spanish), but rapidly adopted
by others. The "traditional" ones employed stone walls and floors, but
modified designs were common and came to include versions with concrete,
wood, and even iron walls (called Chili mills). They were used most
commonly for smaller gold and silver mining ventures, although some of the
larger and more heavily capitalized mines also employed them in tandem with
stamp mills because the arrastras were reputedly more efficient at
capturing fine gold. They were powered by anmials, water, steam, and gas
engines. In some cases literally dozens were used in a single mining
district comprised of one watershed. California Mining Bureau reports imply
thousands were in use in the early days, while hundreds were still used as
late as the turn of the century. Both ore grinding and amalgamation (with
mercury) was usually performed in arrastras. The slurry was then sluiced
out to retrieve the metal, usually via a removable gate or valve in the
wall of the arrastra.

Archaeological examples invariably have floors ripped out because the
cracks in paving trapped gold and deconstruction thus took place upon
abandonment to retrieve those precious deposits. I've never seen a
completely intact example.

An overview is available in the following article:
Kelly, Roger E., and Marsha C. S. Kelly
        1983    Arrastras:  Unique Western Historic Mining Sites.  Historical
Archaeology 17(1):85-95.

I've written a report on two well-preserved, water powered "traditional"
examples made and used by Italians between 1880 and 1895 in central
California (Amador City), if you are interested. We put a trench across one
of them to help define the cross section and design details. Reply off-list
to me if this latter report has any interest to you.

Thad Van Bueren
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-----Original Message-----
From:   Iain Stuart [SMTP:[log in to unmask]]
Sent:   Sunday, May 09, 2004 5:10 PM
To:     [log in to unmask]
Subject:        Arrastra's or arrastre's on mining sites

An arrastra (or arrastre) is defined as a circular rock-lined pit in which
broken ore is pulverized by stones attached to horizontal poles fastened in
a central pillar and dragged around the pit typically by a horse. they are
described as being rare in Australia and unknown in New Zealand.

Recently HLA (the company I work for) has been reviewing a remediation plan
for a silver mine near a town called Emmaville (formerly Vegetable Creek)
and in the report there is a site described as a whim but which looks like
an arrastra (an is too far from the shaft to be a whim).

As a consequence I am now looking for other archaeological examples of
arrastra's from Australia or other countries so I can make an informed
decision on what the site is and its comparative rarity.

yours

Iain Stuart

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