I showed a spectrum to chatgpt (black ink iron gall from yesterday's Joe Barabe's presentation) wondering if provenance of the mined material could be found by comparing ratios of isotope..... here are some replies... has anyone else worked with IA to attach VMS ?
1. What this spectrum actually tells you
Your spectrum appears to be an elemental spectrum from SEM-EDS or XRF. It shows the elements present in the ink spot, for example:
Fe → consistent with Iron gall ink
S → probably from iron sulfate (vitriol)
Hg → possible contamination from Vermilion
Cu / As → possible impurities in vitriol or pigment
K / Ca / Na → salts from parchment or ink preparation
Cl → environmental contamination or parchment treatment
Ti → often modern contamination or environmental dust
This confirms ink chemistry, but elemental presence alone rarely indicates geographic origin.
A. Lead isotope analysis
You already mentioned this.
Example:
Lead isotopes (²⁰⁶Pb/²⁰⁷Pb/²⁰⁸Pb) vary by mine
Used in:
Roman pipes
medieval silver mines
pigments like lead white
But your ink spectrum does not show Pb, so this route may not work unless the ink contains lead pigments.
B. Sulfur isotope ratios
For iron gall inks, the most promising method is often:
Sulfur isotope ratios (³⁴S/³²S)
Why?
Iron gall ink uses vitriol (iron sulfate) mined from:
Spain
Cyprus
central Europe
Italy
Different mines can have distinct sulfur isotope signatures.
Technique needed:
Isotope Ratio Mass Spectrometry
C. Trace element fingerprinting
Vitriol sources contain different trace metals:
Cu
Zn
Mn
Co
Ni
As
Using:
Inductively Coupled Plasma Mass Spectrometry
Laser Ablation ICP‑MS
You can compare the trace metal profile with known historical mines.
This method has been used on medieval inks and pigments.
D. Organic component analysis
Iron gall ink also contains tannins from galls:
oak galls
sumac
other plants
These can be analyzed with:
Gas Chromatography–Mass Spectrometry
Sometimes you can identify plant species or region.
4. What your spectrum might suggest already
The Cu + As + Fe + S combination is interesting.
Many historical vitriol ores contain:
chalcopyrite (CuFeS₂)
arsenopyrite (FeAsS)
These impurities can survive processing.
This could indicate:
natural sulfide ore vitriol
rather than synthetic iron sulfate
But it still does not localize a mine.
1. Iron-gall ink composition is partly geological
Most medieval black ink is Iron gall ink, which typically contains:
Iron sulfate (vitriol) – mined mineral
Tannins from oak galls
Binder (gum arabic)
Water
Of these, the vitriol source is the component most likely to carry a geological signature.
Vitriol historically came from sulfide ore deposits containing minerals such as:
Chalcopyrite
Pyrite
Arsenopyrite
When these weather, they produce iron sulfate, but they also release trace metals.
That’s why your spectrum showing:
Cu
As
Fe
S
is interesting — it may reflect the ore body composition.
2. Trace-element “fingerprints” of vitriol
Different mining regions historically produced vitriol with different impurities.
Examples (general patterns):
Iberian deposits
more Cu
sometimes As
derived from polymetallic sulfides
Central European deposits
often Zn, Mn, Co
Mediterranean sources (Cyprus, etc.)
copper-rich signatures
So if you measure a set of elements like:
Fe, Cu, Zn, Mn, Co, Ni, As, Pb
you can build a multivariate fingerprint.
This is typically done using:
Laser Ablation ICP‑MS
Inductively Coupled Plasma Mass Spectrometry
Quite interesting... chatgpt also 'guessed' it was from the Voynich! and suggested:
The combination:
Cu
As
Fe
could indicate arsenopyrite-bearing ore weathering, which is common in Iberian polymetallic deposits.
That’s not proof — but it’s exactly the type of signal researchers look for.
