Powder diffraction analysis of ancient paint samples
Remark
The huge background originating from the plastic support has been subtracted.
As a result, the diffraction maxima in the 6.8 – 9.2o 2 angle range are
practically lost. This range has been excluded from the analysis. One example of
the initial and the analyzed XRD patterns is shown below for the YMK D4 1
001 measurement.
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Results of phase analysis
Sample
Phase composition
YMK-
Comp. Name
Chemical formula
Remarks
Ref. Code (PDF-4)
%
00-013-0131
30-
from the PDF-file
Hydrocerussite
Pb3(CO3)2 (OH)2
White pigment well known as “white lead”
33
Anhydrite
CaSO4
01-074-1639
25
Colour: white
Weddellite
Ca(C2O4). 2H2O
00-017-0541
5
Colour: Colourless, white, yellowish brown to
brown; powder is white.
Geological setting:
Authigenic in bottom sediments and peat; in
calcareous lacustrine sediments; also formed by
reaction of calcite with oxalic acid derived from
lichens; also from solutions derived from bat guano.
Reference: http://www.mindat.org/
Crandallite
CaAl3(PO4) (PO3OH)
00-033-0257
7 -8
(OH)6
Colour: Yellow, white, grey; powder is white.
Geological setting: Cavities in a quartz-baryte
aggregate.
Reference: http://www.mindat.org/
Gypsum
CaSO4 . 2H2O
01-074-1433
8
Colour: white
Graphite
C
00-033-0257
5
Colour: black
Cristobalite low
SiO2
01-076-0938
3- 4
Colour: Blue grey, brown, grey, yellow, or white;
powder is white
Molybdenite
MoS2
01-075-1539
4- 5
Colour: Black, lead gray, or gray; powder is bluish
gray
Reference: http://www.mindat.org/
Sinnerite
Cu12(As3S7)
01-079-1650
(As5S11)
10
Colour: Bronze, steel-grey, silver; powder is greyblack
Reference: http://www.mindat.org/
Phase Solutions Co Ltd
address: EPFL Start-up
Lausanne, Switzerland
Phone: +41 21 6930630
Fax: +41 21 7289920
e-mail: [email protected]
www.phase-solutions.ch
Sample
Phase composition
GM-R
Comp.Name
Remarks
Chemical formula
Ref. Code
from the PDF-file
(PDF-4)
%
Gypsum
CaSO4 . 2H2O
01-074-1433
32
Anhydrite
CaSO4
01-074-1639
6
Vermilion = cinnabar
HgS
01-089-0438
9
Well known red pigment
Metacinnabar
HgS
01-073-1593
13
Colour: Black, grey-black; powder is black
Reference: http://webmineral.com/data/
Tephrite
(Mg,Al,Fe,Ti)
01-088-0850
Diopside.
(Ca,Na,Mg,Fe) (Si,Al)2
(also
a cation composition. The following
01-072-1379)
elements can be present as a mixture: Ca,
O6
15
Colour of diopside is strongly varying with
Na, Fe(II), Fe(III), Ti, Mg, Al, Mn, Zn, Sc, Cr, V,
Li.
As an example, CaFe(III)AlSiO6 is shown in
the photo.
Reference: http://www.mindat.org/
Weddellite
Ca(C2O4). 2H2O
00-017-0541
13
Colour: Colorless, Tan, White, Yellowish
brown, Brown; powder is white
Reference: http://www.mindat.org/
Wollastonite
CaSiO3
01-072-2297
9
Colour: White, gray-white, light green,
pinkish, brown, red, yellow; powder is white
Reference: http://www.mindat.org/
Graphite
C
00-026-1081
3 (?)
Comp.Name
Chemical formula
Ref. Code
%
Sample
Can be present
Phase composition
Remarks
GM-G-1
from the PDF-file
(PDF-4)
Gypsum
CaSO4 . 2H2O
01-074-1433
77
Moolooite
Cu C2O4. 0.4H2O
00-021-0297
10
Colour: Green The mineral could be a
product of the malachite decomposition
Reference:
Anal. Chem. 2008, 80, 4103–4110
Green Copper Pigments Biodegradation in Cultural Heritage:
From Malachite to Moolooite, Thermodynamic Modeling, X-ray
Fluorescence, and Raman Evidence
Graphite
C
00-002-0456
2
Anhydrite
CaSO4
01-074-1639
3
Cu2PO4
01-083-1068
Some of
CuSO4
01-072-1248
these
Mg2P2O7
00-008-0038
compounds
CaSnO3
00-034-0939
can be
Chalcocyanite
(rhombohedral)
Phase Solutions Co Ltd
address: EPFL Start-up
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present in
e-mail: [email protected]
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CaSnO3
01-075-0463
(cubic)
Malayaite
CaSn(SiO4)O
the sample
within 1-2%.
00-025-0176
However,
Coloure: Pale creamy-yellow, deep orange-
their
yellow
diffraction
peaks are
Romarchite
SnO
01-085-0712
weak and
overlapped
with each
other and
with peaks of
main
Colour: black.
Associating minerals: malachite,
Cu2(CO3)(OH)2 , cuprite, Cu2O, and
cerussite, PbCO3.
Reference: http://www.mindat.org/
components
(see graphic
illustrations
for GM G 1)
Egyptian blue
Sn(HPO4)2. H2O
00-031-1397
CaCuSi4O10
01-074-0828
“Possibly the most famous of all synthetic
pigments made in Ancient Egypt … is
created by heating quartz (desert sand),
calcium (limestone), small amounts of alkali
(plant ash, potash, or the desert salt
'natron') and copper carbonate (particularly
malachite) ….”
Reference:
http://africanhistory.about.com/od/hierogl
yphs/a/ColorTech_2.htm
Tennantite
Cu12As4S12
01-076-0101
Colour: Grey-black, steel-gray, iron-gray,
black; powder can be Reddish grey, black,
red-brown
Reference: http://www.mindat.org/
Apatite-like compound
Ca.Pb-phosphate
Calcite magnesian
Mg0.1Ca0.9CO3
01-071-1663
Diopside
(Ca,Mg,Fe)2
01-083-0092
Si2O6
Phase Solutions Co Ltd
address: EPFL Start-up
Lausanne, Switzerland
Phone: +41 21 6930630
Fax: +41 21 7289920
e-mail: [email protected]
www.phase-solutions.ch