#30 – What Rock is It?


You would think that everyone could at least agree on the kinds of stone used to make the artifacts from the cave. Yet the geologists’ reports have differed greatly.

Of course, with so many artifacts to choose from (several thousand, once, though there are fewer than 200 now in Burrows’ hands), there is no certainty that the same few types of stone were used for all. And it’s likely that, over a decade of various analyses, different stones were examined at different times. But granting all that, the variance in conclusions is nonetheless startling.

Here’s a summary of what different people have said at different times.

1) (1991): First, to orient you, here’s a simple description, by James Scherz, a civil engineering professor with some professional knowledge of geology. He describes the current Burrows collection as consisting mainly of palm-sized, turtleshell-shaped stones; almost all are black or dark grey. Some of them resemble black slate, shale, or similar soft and layered material. Other black pieces are of a harder material. (#65)

2) (1986): Jack Ward, a retired gravel salesman, who should have known his stone, said that the majority of the pieces (in those days, several thousand that he had in his possession, or had seen) were of two varieties: diorite and limestone. (#29,65)

Diorite is a granular crystalline igneous rock. (Ward said these pieces of diorite were sand-eroded, and had long lain on the surface of the Egyptian desert.)

Limestone is formed from organic animal remains (mainly shells or coral), consists mainly of calcium carbonate, and can vary greatly in hardness. Judging from the Field Museum letters, Ward claimed that the rock he called limestone was, more specifically, nummulitic limestone, which is the most widely distributed and distinctive formation of the Eocene in Europe, Asia, and northern Africa.

Burrows, though no geologist, has studied caves and explored many. He thinks the cave from which the artifacts came is a limestone cave, with a sandstone cap. (#17)

So, diorite and limestone, according to Ward.

3) (1986): The Field Museum experts included one petrologist (Woodland), and several others who thought themselves competent to speak on geology as it touched on their fields. They said they examined stones of two or three types, which Ward called diorite and nummulitic limestone. In their opinions, these stones were in actuality:

(Woodland): a fairly crystalline marble (a metamorphic rock not found in Illinois or adjacent regions); a soft black shale – not an igneous rock like diorite; and a carbonate concretion which had formed in black shale this also of sedimentary origin.

(Pickering): whitish marble (possibly from gravestones) – not lime-stone; and shale/slate – not diorite.

(Yurco): a crystalline marble – not nummulitic limestone; and a schist or a shale – not basalt. (Basalt is a dark gray to black dense to fine-grained igneous rock.)

(Sease): made no pronouncement, but assumed the pieces she examined were marble.

(The Field Museum scholars hooted at Ward for, in their opinion, grossly misidentifying the stones.)

So, shale and marble, according to the Field Museum experts. (#29)

4) (1986): Virginia Hourigan showed samples around.

Jim Whittall examined one under a microscope; this had a face with a sort of hat on top. The edge of the hat was a thin line of quartz, “so thin you couldn’t disturb it without breaking it, and the quartz was formed around a pebble that went right through it in the middle of the face’s forehead.”

Geologist Virginia Ross looked at the samples Hourigan showed at the Early Sites meeting. She could make an impression in one with her finger-nail, giving it a hardness of 4 (out of 10). She thought them siltstones.

(Burrows, obviously speaking of a different type of rock altogether, had reported that he broke a diamond drill bit on one piece.)

Norman Nielsen, a retired materials engineer, with access to the DuPont labs, did several tests: a nondestructive test on an unnamed sample, and a later destructive test on a broken ushabti” that Cullen had had on his windowsill in the sun.

Ward and Cullen had rubbed this piece with car wax and wiped off the excess with lighter fluid: all this to make the inscriptions stand out more clearly.

Nielsen found the wax and concluded he was dealing with a man-made stone. He sent the report to Whittall, but Hourigan didn’t hear about it until 1990.

Another engineer, James Guthrie, later analyzed the same ushabti stone, and concluded the stone was natural and the wax a later addition.

Two geologists from the American Museum of Natural History said one of the samples Hourigan had was argillite (a siltstone), and all the samples were fairly soft.

Hourigan says other stones (not the ones analyzed) are harder, with a “core” of a different texture and color. (#38)

5) (1986): John Ward gave a stone to Gloria Farley in the summer of 1986. This was analyzed by W. Dale Murphy, a petroleum geologist in Denver. He reported that the stone was a fine grained siltstone.

6) (1991): Rydholm, Burrows, and Trawicky visited the Wisconsin Geological Survey, and showed samples to two geologists there. They were open and helpful. They said the samples that had been pronounced “slate/shale” were in fact lithographic limestone. And one highly polished piece was basalt. (#65)

A conglomerate of jumbled results, no?