In Search of the Boston Green Head, Part One: Basanite, Bekhen Stone, and the Wadi Hammamat
A moody and weird Julius Caesar, probably Egyptian, probably from the century or so after his death
This is the first of several posts related to a particular type of stone, and a small bust of an Egyptian priest made from that stone, in the Boston Museum of Fine Arts.
A few years ago I was browsing through Philip Matyszak's Chronicle of the Roman Republic (a series of short biographies of various figures during that era, with informative sidebars, stemmata, and timelines, it is made for browsing, at least if you are a Roman history geek), when I came across a picture of this striking bust of what is most likely Julius Caesar, in Berlin.
The caption in the book says it is carved from green "basanite", a stone from Egypt. Clearly the stone is sculpturally useful, dense, hard, of consistent texture, capable of being smoothed, and of striking color.
I've written about sculpture before, and am toying with a book about a sculptor in the late 19th century. So I was curious: what is basanite? Sculpture is the encounter between an idea and a specific physical reality. Well, OK, that describes art in general, but it seems clearest in the case of sculpture, whether stone, wood, metal, or clay, each of which is a demanding partner in the work.
But the identity of basanite is not as easy a question to answer as you might think.
The mysteries of geologic nomenclature
The stone in question is not always called basanite, and the history of the word "basanite" itself can cause confusion as well—after you read my detective work, I will reveal that the criminal is actually someone completely different. The material of the bust called the Green Caesar is sometimes described as greenschist, slate, or greywacke.
As we shall see later on, there is a completely different stone, an igneous extrusive called basanite, and which confused me for a long time. Here, "extrusive" just means the igneous rock formed on the surface, rather than underground. Confusingly to laypeople, geologists often give completely different names to the extrusive and intrusive versions of otherwise identical rocks—for example, what is granite when it forms deep underground is rhyolite if it forms on the surface. This igneous basanite is very much like basalt (an extrusive igneous rock whose intrusive version is called gabbro, if you must know).
There are also historical reasons this rock is called basanite, but the rock the head is made of is something else entirely. For now, I will call that stone "sculptural basanite" (a term of no validity outside this blog post—let it be our secret), though I will come up with a more precise name a bit further on, though be warned that that name will be just as much of a local variable as sculptural basanite.
On the track of sculptural basanite
In The Materials of Sculpture (an informative book covering stone of all kinds, as well as ivory, bronze, clay, and wax, among other things) Nicholas Penny says
The most highly prized Egyptian stone to be employed for sculpture on a large scale was basanite, commonly confused with basalt (and still usually described as such on museum labels [the book is from 1993]). This is a "greywacke", a by-product of the decomposition of basaltic rock.
"Decomposition" is geologically imprecise, but this places the stone at its place of origin, Egypt, and also demonstrates how the terminology can be vague or confused (it is the other kind of basanite that can be confused with basalt). Unfortunately for interested amateurs like me, geology has no equivalent of a species, where there is only one name for one thing, and the first discoverer gets absolute naming priority. Rock types are not even as clear a species, and it feels like there was always a lot of competitive naming going on in geology, with everyone convinced that the rock in their mountains was quite different than that allegedly similar rock in those mountains some sadly lame earlier geologists wasted their time investigating.
In "The building stones of ancient Egypt – a gift of its geology" (PDF), Klemm and Klemm say
green siltstones, dark green greywackes and conglomerates, which are best exposed in the Wadi Hammamat...[where] an impressive quarrying activity is documented by almost 600 rock inscriptions over a time interval from Predynastic until the late Roman period (about 4000 BC until 300 AD). These many inscriptions concentrated along a relative short distance in the wadi obviously indicate the uniqueness of this site and its extraordinary importance to ancient Egyptian culture. Consequently the rock type extracted here received a special name: ‘‘Bekhen-stone’’, as reported in many ancient Egyptian documents.
This Bekhen-stone is the basanite I got interested in. The Wadi Hammamat, far off in the Eastern Desert, required long overland transportation to the Nile, under difficult, waterless conditions. But I am not alone in being struck by the character of this stone:
Particularly the very dense, medium-grained dark green greywacke was used during the entire Pharaonic era and on until the Ptolemaic (Greek) period (from 332–30 BC), mainly for sarcophagi, archetraphes [sic— I'm assuming they mean "architraves", but am not sure] and for the finest carved sculptures of Egyptian antiquity. Scattered unfinished or broken sarcophagi indicate that at least the raw form of these vessels were worked out at the quarry site, which is understandable as they had to be transported over 90 km through the desert, until shipped on the river Nile to their final destination.
Most of the royal sarcophagi of the [Old Kingdom] and about 100 sarcophagi for private individuals of the Late Period (since 600 BC) and of Ptolemaic and Roman times were made of this rock variety.
Wadi Hammamat should totally be more famous
The Wadi Hammamat is totally cool, historically, geologically, and geographically, and has to have been the setting for some historical fantasy or other. Anyone know of one? My reading in that genre is pretty sparse.
OK, that's enough for now. Next time, we finally distinguish sculptural basanite from basalt, and then have a look-in on its dark twin, sculpturally useless igneous basanite. I bet you can't wait.