Quartz hydration dating.

[Jacques Cinq-Mars]

All,

Given the time range mentioned in the following relase, this new dating method/technique should be of great help in dealing with the elusive timing and nature of the so-called "MP/EUP transition. That is, assuming that it will not be as capricious as obsidian hydration dating.

Jacques Cinq-Mars

New method for determining age of artifacts fills chronological gap for scientists

Quartz hydration dating opens window on 50,000-year time period difficult to measure with other dating methods

University of California, Irvine, Calif., April 12, 2004

A UC Irvine archaeological scientist has created a new method for determining the approximate age of many artifacts between 50,000 to 100,000 years old – a period for which other dating methods are less effective.

In a recent study in the Journal of Archaeological Science, Jonathon Ericson, professor and chair of UCI’s Environmental Health, Science and Policy Department, and colleagues introduce a new mineral dating technique called quartz hydration dating. The technique dates artifacts containing quartz, a common mineral found in almost every type of rock.

Quartz hydration dating is based on a natural phenomenon that occurs when a piece of quartz is fractured. When a statue or a common chopping tool or hand ax is made, the surface is chipped, flaked, fractured or polished. Over time, water diffuses into the freshly exposed surface forming a hydration layer. The thickness of this layer can then be measured by a nitrogen particle beam to determine how many years ago the object was made or fractured naturally.

According to Ericson, quartz hydration can date objects that are between 100 and 1 million years old to within 20 to 35 percent of the object’s age. Quartz can be found at archaeological excavation sites worldwide from Africa’s Olduvai Gorge to China’s Choukoutien and even California’s Mohave Desert. A ubiquitous mineral, quartz was used in toolmaking from the beginning of human history and also can be found in statues, bowls and ceramics.

The new method, however, is particularly useful for dating quartz-containing artifacts in the “chronological gap” that exists for objects that are between 50,000 to 100,000 years old. Other dating methods are poor performers for this period or have questionable accuracy, and the most familiar dating methods are not effective at all. Radiocarbon dating is good for dating organic material up to around 50,000 years old, and potassium argon dating is good for dating mineral samples that are between 100,000 and 4.3 billion years old.

Forged artifacts also can be tested with the quartz hydration dating technique. With replications of statues for example, the thinness or lack of the hydration layer will give away their age. The technique may also have applications for dating geological events, such as an earthquake rupture, which would cause natural fracturing of quartz.

“What is so exciting about quartz hydration dating is that it opens up the possibilities of dating other minerals, which could lead to a whole new class of materials and processes that could be dated,” Ericson said.

Ericson’s colleagues in the study are Oliver Dersch and Friedel Rauch of the Institute for Nuclear Physics at the Johann Wolfgang Goethe University in Frankfurt, Germany. Partial funding for this study was provided by the National Science Foundation.

[Jacques Cinq-Mars]

All,

Given the time range mentioned in the following relase, this new dating method/technique should be of great help in dealing with the elusive timing and nature of the so-called "MP/EUP transition. That is, assuming that it will not be as capricious as obsidian hydration dating.

Jacques Cinq-Mars

All

Sorry about this reply to myself. Here is some additional info on "quartz hydration dating" with a few cautionary comments from
Alan Watchman. Nonetheless, I am looking forward to reading the actual paper.

Jacques Cinq-Mars

Dating quartz unearths human secrets

Heather Catchpole

Tuesday, 27 April  2004 -News in Science - ABC Science Online


A new way of dating quartz could help archaeologists better date objects from a key period in history when modern humans first roamed the Earth, according to U.S. and German scientists.

The technique is most accurate when dating objects between 50,000 to 100,0000 years old, the researchers said.

Professor Jonathon Ericson from the University of California, Irvine and colleagues from the Johann Wolfgang Goethe University in Frankfurt published details in the latest issue of the Journal of Archaeological Science.

Quartz is extremely common at archaeological sites and is used in tools and well as statues, bowls and ceramics.

The new technique is similar to one currently used to date obsidian, a type of volcanic glass.

The technique relies on the absorption of water into a freshly cut surface of the mineral, forming a rim of hydrated quartz. The thickness of the rim reveals how long the surface has been exposed.

The technique can be used to date objects between 100 and one million years old and is accurate to within 35% of the object's age, the researchers said.

Although the researchers admitted the error margin was large compared with other dating techniques, they said in some circumstances the margin could be brought down to 20%.

In cases of forgeries, even a large margin of error would be sufficient to spot fakes, the researchers said.

Australian archaeologist Dr Alan Watchman from the Australian National University in Canberra was concerned with the large error margin.

"[A margin of] 35% is excessive and we wouldn't accept that. We look for 2-5%," he said.

For radiocarbon dating, which uses the ratio of different forms of carbon in an object, the error for a 5000 year old artefact was about 60 years, he said.

But he said carbon dating was limited in that it could only go back about 45,000 years.

"For Australia and North America that might be OK, but for other places, or if there is no carbon present, we need other dating methods," Watchman said.

But he said there were inherent problems with the quartz technique, which the authors acknowledged, including the effect of temperature and hydration history on the object being dated.

"Say an artefact has been sitting on the surface in a desert and it heats up to 50ºC during the day and drops to 0ºC at night. That sort of temperature fluctuation has an effect on the hydration of the quartz," Watchman said.

But if there was no other indication, then a date with 35% error was a good initial estimate, he said.

"It might be useful, for example, in a cave situation where temperature and water regime were constant. In that situation the error could come down to 5 or 10%."

[Ellery Frahm]

...I am looking forward to reading the actual paper.

So am I -- thanks for the heads-up, Jacques.

Ellery

[Jacques Cinq-Mars]

So am I -- thanks for the heads-up, Jacques.

Ellery

Ellery,

Thanks for being around and for the "thanks", but I must say that a less cryptic message would certainly be appreciated.

Jacques

[Ellery Frahm]

Thanks for being around and for the "thanks", but I must say that a less cryptic message would certainly be appreciated.

Sorry, I didn't mean to be "spammish" or cryptic.

Anyway, for those interested, here is the abstract for this paper:

Journal of Archaeological Science
Volume 31, Issue 7 ,  July 2004,  Pages 883-902

Quartz hydration dating

Jonathon E. Ericson, Oliver Dersch, and Friedel Rauch

Abstract

Archaeological quartz artifacts and naturally fractured quartz fragments occur in a variety of cultural and geological contexts worldwide. For dating such objects we have developed the new Quartz Hydration Dating (QHD) technique. It relies on the phenomenon of water diffusion into quartz leading to the formation of a hydration layer that can be measured by a hydrogen profiling technique, and diffusivity data connecting the layer thickness with the hydration time. We have obtained such data by induced-hydration experiments in the temperature range 60 to 200 °C and derived a general equation for calculating diffusion coefficients which was validated by results from dated artifacts. The main factors influencing the diffusivity are temperature, the crystallographic orientation, measured as the angle between surface of hydration and crystal c-axis, and initial H content of the quartz. The experimental results are discussed in the frame of a diffusion-reaction model from the literature. The time range of QHD is 100 ya to over 100K ya. The error of age determination is 35%, but may be reduced to 20% by controlling for material variability. QHD is applicable to single-crystal specimens and aggregates of single crystals. Apart from its application to archaeology and geology, the technique is suited for detecting fakes.

Author Keywords: Author Keywords: Quartz; Quartz artifacts; Hydration dating; Diffusion; Water

[Jacques Cinq-Mars]

Sorry, I didn't mean to be "spammish" or cryptic.

Anyway, for those interested, here is the abstract for this paper:

No need to apologize, thanks for the reference to the paper, and glad to read you again. Now, I'll read the article.


Jacques Cinq-Mars

[Jacques Cinq-Mars]

Dear Ellery,

Just did a quick read of the paper. This dating technique -- obviously experimental and presented as such -- reminds me in some ways of a few brief encounters I have had with cosmogenic dating. A lot of assumptions and such a low level of resolution that it appears to be somewhat promising only in the case of very great chronological distances which in many instances, can be assessed through a broad range of other approaches and techniques But then, what the paper is about is clearly “work in progress”, and we have to assume that application niches, in both archaeology and geology fields, will eventually become more focussed, complementary to other techniques, practical, and economically viable.

This said, I am certainly willing to stand corrected, re: my somewhat "blasée" reaction to the paper.

Jacques