Identification of pigments and binders of a 17th century mural painting (Bolivia). New report on pigments associated with Andean minerals

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Iden i ica ion o pigmen s and binde s o a 17 h
cen u y mu al pain ing (Boli ia). New epo on
pigmen s associa ed wi h Andean mine als.
Eugenia Tomasinia*, Ila ia Cos an inib, Vale ia Ca eagac, Ca los Rua Landad, Kepa Cas ob,
Juan Manuel Mada iagab, Ma a Maie a,c, Gab iela Si acusanoa.
a CONICET, Cen o de In es igación en A e, Ma e ia y Cul u a, IIAC, Uni e sidad Nacional de T es de Feb e o, A da. An á ida
A gen ina 1355 (C1104ACA), Ciudad Au ónoma de Buenos Ai es, A gen ina. euge[email p o ec ed] , [email p o ec ed]
b Depa amen o de Química Analí ica, Facul ad de Ciencia y Tecnología, Uni e sidad de País Vasco UPV/EHU, P.O. Box 644, 48080
Bilbao, España. [email p o ec ed], [email p o ec ed], ju[email p o ec ed].
c UMYMFOR-CONICET, Depa amen o de Química O gánica, Facul ad de Ciencias Exac as y Na u ales, Uni e sidad de Buenos Ai es,
Pabellón 2, Ciudad Uni e si a ia, (C1428EGA), Ciudad Au ónoma de Buenos Ai es, A gen ina. [email p o ec ed],
[email p o ec ed].
d Minis e io de Cul u as y Tu ismo, Talle de Conse ación y Res au ación del Pa imonio Mueble, Ayacucho S/N, La Paz, Boli ia.
[email p o ec ed]
* Co esponding au ho . Tel.: +54 1148930625. eugenia [email protected]
Abs ac
Resea ch on he ma e iali y o Andean Colonial a is ic he i age con ibu es o he knowledge on he cul u al
and social his o y o he egion. In his wo k we p esen he esul s o an in e disciplina y and mul i-analy ical
in es iga ion on a mu al pain ing o he chu ch o Cu ahua a de Ca angas in Boli ia. This pain ing has been
hidden o yea s behind he main 18 h cen u y wooden al a piece. I s s ylis ic and pic o ial cha ac e is ics
place i in he ea ly 17 h cen u y (1608), while o he mu al pain ings o he emple co espond o a second
s age, by 1777. Pigmen s we e iden i ied by scanning elec on mic oscopy wi h ene gy dispe si e X- ay
spec oscopy (SEM-EDS) and Raman mic o-spec oscopy. The applica ion o imaging me hods no only
allowed he iden i ica ion and cha ac e iza ion o he ma e ials bu also ga e in o ma ion on he
manu ac u ing echnique o his mu al pain ing. An ou s anding inding in ou wo k was he iden i ica ion o a
mix u e o wo coppe mine als, a acami e [Cu2Cl(OH)3] and an le i e[Cu3SO4(OH)4], as he g een pigmen .
A acami e and an le i e ha e been sepa a ely iden i ied in a polych ome sculp u e and a mu al pain ing,
espec i ely, bu his is he i s epo on hei use as a mix u e. O he pigmen s iden i ied in he mu al
pain ing we e hema i e, azu i e, ed lead, cinnaba , gypsum, ce ussi e, o pimen , and ca mine lake. These
esul s, oge he wi h he iden i ica ion o aces o mine als o he egion, indica e he use o local ma e ials
by Andean pain e s om he ea ly Colonial pe iod. This sugges s con inui y in he cul u al p ac ices om p e-
Hispanic imes and an app op ia ion and e o mula ion o adi ional Eu opean pain ing p ac ices adap ed o
new esou ces. Analysis o lipid and p o ein ma e ials by gas-ch oma og aphy coupled o mass spec ome y
This is he accep ed manusc ip o he a icle ha appea ed in inal o m in Jou nal o Cul u al He i age 62 : 206-2016 (2023), which has
been published in inal o m a h ps://doi.o g/10.1016/j.culhe .2023.05.030. © 2023 Consiglio Nazionale delle Rice che (CNR). Published
by Else ie Masson unde CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-nc-nd/4.0/)
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(GC-MS) indica ed he use o a secco pain ing echnique in ol ing he use o egg as pigmen binde .
Iden i ica ion o animal glue sugges ed i s use as he plas e p ime . The knowledge o he ma e ials and he
pain ing echnique o his a wo k will allow he iden i ica ion o simila i ies and di e ences wi h o he mu al
pain ings in chu ches o he Andean egion and gi e use ul in o ma ion o conse a ion and p ese a ion o
his a wo k.
Keywo ds
Pigmen s analysis; Mapping SEM-EDS; Raman imaging; Mu al Pain ing, Spanish Ame ican Colonial a .
Highligh s
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 Analyses wi h complemen a y echniques we e applied o he old pain ed al a co esponding o he
i s deco a ion o he chu ch o Cu ahua a de Ca angas (O u o, Boli ia), appa en ly made a ound
1608 and which emained hidden o yea s behind he wooden al a piece o he 18 h cen u y.
 The applica ion o SEM-EDS and Raman imaging me hods p o ided use ul in o ma ion o iden i y
and s udy he dis ibu ion o pigmen wi hin each pain laye as opposed o spo analysis.
 The use o a mix u e o a acami e wi h an le i e and he p esence o minium and e milion in a mu al
o he Colonial pe iod has ne e been epo ed be o e.
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1. In oduc ion
1.1. P e ious s udies o Andean Colonial mu al pain ings
The s udy o Andean Colonial a is ic he i age con ibu es o he knowledge o he cul u al and social his o y
o he egion. As pa o an in e na ional and in e disciplina y p ojec on he mu al pain ings o se e al
Andean Colonial chu ches, buil be ween he 17 h and 18 h cen u ies, se e al chemical and a his o ical
s udies we e ca ied ou [1–7]. The chu ches we e loca ed on he Ru a de la Pla a (Sil e Rou e), a oad ha
was used o anspo me cu y and sil e mine als om he ci y o Po osi (Boli ia) o A ica (Chile) on hei
way o Spain ia Panama.
This ou e also se ed o ade possessions and p oduc s, as i communica ed impo an ci ies such as
Cuzco, A equipa, La Paz and Suc e. This mo emen o people and cul u es p omo ed, in he Andean
communi ies along he oad, he a chi ec u al and a is ic s yles o he main chu ches o he Sil e Rou e [6].
Chu ches wi h mid-18 h cen u y Colonial mu al p og ammes a e p ese ed in his a ea: Nues a Seño a de
Copacabana de Andama ca, San iago de Cu ahua a de Ca angas, San iago de Callapa, and San José de
So acachi in Boli ia, as well as San And és de Pachama in Chile, among o he s. These pain ings a e ound
on he walls o he na es and ea u e deco a ions wi h ases o lowe s, ui s, and bi ds, along wi h eligious
iconog aphies de eloped o con ibu e o he e angelisa ion o he local popula ion. P e ious a his o ical
s udies ha e paid a en ion o hei iconog aphic p og ams, hei co espondence wi h w i en sou ces and
o al p ac ices like se mons, as well as hei conse a ion s a us. [8–12]
Wi h he aim o in es iga ing he ma e ials and he pic o ial echnique o he mu als o he chu ches on he
Sil e Rou e, ques ions we e asked abou his o y, chemis y and conse a ion, which ga e ise o se e al
esea ch p ojec s published in specialised jou nals[1–3,13–15]. The o iginal emaining sec ions o hese
pain ings (o he pa s ha e been es o ed) show li le ch oma ic changes, al e a ions, o deg ada ion
phenomena hanks o he clima ic and geog aphical condi ions o he Andean highlands, which p o ed o be
na u al agen s o p ese a ion.
In o de o iden i y and cha ac e ise he colou pale e and in es iga e he echnique o hese mu al pain ings,
analyses we e ca ied ou using di e en echniques. Op ical mic oscopy (OM) was used o isual and
mo phological analysis and scanning elec on mic oscopy wi h a coupled p obe o ene gy dispe si e X- ay
spec oscopy (SEM-EDS) o an elemen al analysis o he a ea unde s udy. Fou ie ans o m in a ed
spec oscopy (FTIR-ATR) and mic o-Raman spec oscopy we e used o molecula analysis. On he o he
hand, analysis o o ganic dyes was accomplished by high pe o mance liquid ch oma og aphy (HPLC) while
lipidic and p o ein binde s we e analysed by gas ch oma og aphy coupled o mass spec ome y (GC-MS).
The de elopmen and applica ion o a me hodology ha emphasises he in e disciplina y and mul i-analy ical
app oach made i possible o es ablish he pigmen pale e and ob ain p ecise and de ailed in o ma ion on
he echnique o mu al pain ings in 16 h-18 h cen u y chu ches on he Sil e Rou e.
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A se ies o i on oxides used as och e pigmen s we e e ealed. Yellow o ed ea hs (limoni e, goe hi e, and
hema i e) we e widely used as pigmen s o hese colou s in he Andean egion. Hema i e o almag e has
been iden i ied as a pigmen highly used in Colonial pain ings [16–19] as well as o he base p epa a ion in a
polych ome sculp u e, being pa o he "bol a menio" along wi h o he compounds such as clays [20]. These
ha e been iden i ied in mos o he mu als whe e och e shades we e used, usually wi h qua z o mixed clays
ha a e a ailable in he egion.
O pimen , an a senic sulphide (As2S3), is shown in i s yellow colou in some o he mu als. This was one o
he mos app ecia ed pigmen s used in he Andean Colonial pale e, despi e i s poisonous cha ac e [18]. I
was no only used as a yellow colou , bu also in mix u es wi h indigo o P ussian blue o ob ain di e en
shades o g een [16–19,21]. O pimen has also been de ec ed in mos o he illus a ions in he 17 h cen u y
manusc ip o Ge y Mu úa's His o ia Gene al del Pi u [22] and i s disco e y in une a y objec s o a woman
ound in an ancien bu ial si e a Cho illos in Chile indica es he a ailabili y o o pimen as a pigmen since
p e-Hispanic imes in he Andean egion [23].
A ed pigmen widely used in he Andean a ea was also e milion (HgS). I was ound in he mu als o he
chu ches o San And és de Pachama, Cu ahua a de Ca angas and San José de So acachi, and in o he s
along he Sil e Rou e oge he wi h he p esence o haema i e [2,24]. Al hough in gene al he analy ical
s udies ca ied ou do no di e en ia e be ween he mine al (cinnaba ) and he syn he ic compound, he
samples showed he p esence o impu i ies, such as silica es, which may occasionally be associa ed wi h he
mine al, indica ing a na u al o igin. The sou ce o cinnaba in Ame ica was he mines o Huanca elica and
o he s nea Guamanga in Pe u [25], and i s use p io o he a i al o he Spanish in he egion is p o en in
mo ua y con ex s and especially as body pain in Pe u in i uals and sac ed ce emonies [18,26,27]. La e , i
eappea s in se e al Colonial polych ome pain ings and sculp u es as is well known [16,17].
On he o he hand, in he mu al pain ings o he chu ches o Pachama in Chile and O u illo and Ma capa a in
Pe u, he use o a da k ed colou was obse ed and he use o ca mine lake was iden i ied [28]. This dye is
a ed lake p epa ed om ca minic acid, which is ound in he insec Dac ylopius coccus Cos a known as
cochineal. I s p esence was con i med by HPLC in a mic o-des uc i e way and wi h p e ious p epa a ion
hyd olysis in acidic me hanol [29]. Cochineal has been used as a ex ile dye since p e-Inca imes and as a
pigmen in pain ings, sculp u es and Colonial ex ile objec s om he 17 h and 18 h cen u ies [16,18,29]. This
inding p o ided new in o ma ion on he use o ca minic acid lake as a pigmen in Colonial mu al pain ings.
Ano he na u al o ganic dye iden i ied was indigo, which is p epa ed om he e men a ion in wa e o plan
lea es, mainly o he species Indigo e a inc o ia, and has been one o he mos widely used blue pigmen s
as e idenced by i s iden i ica ion in se e al 18 h cen u y pain ings in Sou h Ame ica [22,30–32]. Al hough
indigo was aded om di e en pa s o he Ame icas, mainly Cen al Ame ica, he exis ence o a local
ma ke in he s udy a ea canno be uled ou due o he high demand, especially o dyeing and pain ing
can ases [18]. The p esence o indigo was a cons an disco e y in mu als in Boli ia, Chile and Pe u, and in
all cases i s g ea s abili y and deep one is a phenomenon ha is s ill being in es iga ed [1,2,24]. Ano he
blue pigmen ound, less equen ly, was smal , which was p oduced in Eu ope by oas ing cobal mine als o
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ob ain cobal oxide. I was no p oduced in he Vice oyal y o Pe u, so i p obably had o be impo ed om
Eu ope [33]. As pa o ou esea ch on he ch oma ic pale e o Colonial wo ks o a , smal has been
iden i ied in se e al 17 h and 18 h cen u y Andean pain ings and in he man le o he Vi gin o he gilded
polych ome sculp u e o Ou Lady o Copacabana in Boli ia, among o he esea ch [30,34].
The iden i ica ion o he use o wo basic coppe sulpha es: an le i e (Cu3SO4(OH)4) and b ochan i e
(Cu4SO4(OH)6) as g een pigmen s is highligh ed [1,2,6]. The local a ailabili y o bo h sulpha es, hei
he e ogeneous composi ion, he na u al mix u e wi h o he oxides and he c ys allini y in he wall pain ing
samples poin o a mine al o igin o he pigmen an le i e. This was he i s ime hese mine als we e
iden i ied in Colonial a . This inding expanded he knowledge abou he pale e o g een pigmen s ha ou
in e disciplina y g oup had al eady iden i ied in Colonial easel pain ings and polych ome sculp u es
[16,17,19,20,35]. These mine als we e a ailable in he A acama Dese in no he n Chile, which is ich in
coppe mines exploi ed since p e-Hispanic imes [36,37]. On he o he hand, coppe mine al-based pigmen s
ha e been iden i ied in g een pain s on p e-Hispanic animal hide masks in he egion [38].
The s udy o he black pigmen s o he mu als ga e ise o se e al in es iga ions in o ca bon-based black
pigmen s in o de o be e de ine hei ma e ial cha ac e isa ion and p o ide possible pa hs o iden i ying
hem h ough he use o di e en echniques [13,14,39]. This p oposal was en iched by he c oss- e e encing
o di e en his o ical sou ces ha allowed he s udy o he p ac ices associa ed wi h he manu ac u e o
hese pigmen s. A he same ime, hese p o ided indica ions o he symbolic signi icance o he colou black
in he Spanish-Ame ican Colonial pe iod [40]. This me hodology was applied o di e en samples o black
a eas o se e al mu als and i was ound ha all o hem coincided wi h he use o cha coal.
Rega ding he manu ac u ing echnique, we ha e de e mined in se e al Andean mu als he use o gypsum
as a p epa a ion g ound on he adobe walls o he chu ches and iden i ied an animal glue, p esumably used
as a p ime o he gypsum laye [1,2,28,42], in acco dance wi h ecommenda ions o a secco pain ing
echnique in a ea ises [43]. Recen ly, we ha e iden i ied muscle p o eins oge he wi h collagen in mic o-
samples om mu al pain ings in wo 18 h cen u y Andean chu ches in Chile [44]. This inding poin s o a
local p epa a ion o he glue, p esumably using was e om cow and icugna, a domes ica ed camelid used
as ood and o anspo a ion in he Andean egion since p e-Hispanic imes. In addi ion, a y acids and
choles e ol we e also iden i ied, e ealing he use o a mix u e o ege able oil and egg ( empe a g assa) as
he pigmen s´ binde .
These esul s and ou p e ious indings sugges a p e e ence o he use o mine als as pigmen s in Andean
chu ch wall pain ings, sugges ing a na u al o igin o he pigmen s and he de elopmen o echnological
p ac ices o hei p oduc ion in he Andean egion since p e-Hispanic imes. The eason o his selec ion
may be ela ed o he local a ailabili y o hese mine als compa ed o o he s.
1.2. Resea ch aim
This pape p esen s he esul s o he analysis wi h complemen a y echniques (mic o Raman spec oscopy,
scanning elec on mic oscopy-ene gy dispe sion spec oscopy (SEM-EDS), high pe o mance liquid-
ch oma og aphy wi h diode-a ay de ec ion (HPLC-DAD) and gas-ch oma og aphy coupled o mass

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spec ome y (GC-MS) o he o me pain ed al a ound in he chu ch o Cu ahua a de Ca angas (O u o,
Boli ia) [45]. This mu al became isible when es o a ion wo k was ca ied ou in 2011, a e ha ing been
hidden o yea s behind he main wooden al a piece since he 18 h cen u y. I ep esen s he p esen a ion in
he Temple and Pu i ica ion o Ma y, ollowing a Flemish p in by Lucas an Doe ecum a e Ge a d
G oenning, and i co esponds o he i s deco a ion o he emple, appa en ly done by 1608 (Fig. 1).
The cha ac e iza ion o he ma e ials and pic o ial echnique in his mu al pain ing will allow o iden i y
simila i ies and di e ences wi h p e ious esul s on Andean Colonial mu al pain ings and o con as hem
wi h he a is ic li e a u e o he pe iod. Mic o-sampling in damaged a eas was ca ied ou o his wo k.
Al hough he sampling could be conside ed in asi e, only a minimum numbe o ma e ials was aken.
Indeed, he mic oimaging and mic ospec oscopy echniques employed allowed ex ensi e s udies on a
mic ome ic single sample. This analysis can be done di ec ly on he su ace o in each laye in c oss-
sec ions o he sample. These c oss-sec ions will be pa o he sample pa imony a chi e o he Cen o de
In es igación en A e, Ma e ia y Cul u a (Cen o MATERIA) o he Uni e sidad Nacional de T es de Feb e o
(Buenos Ai es, A gen ina) and will be made a ailable o u u e analysis.
Many he i age objec s a e c ea ed wi h a wide a ie y o ma e ials, and hey o en p esen he e ogenei ies a
di e en scales. In his sense, spec oscopic echniques equipped wi h imaging capabili ies a e use ul
because he in o ma ion ob ained allows o unde s and he ma e ials and p oduc ion echniques, as well as
he de e io a ion o he objec s in o de o plan be e s a egies o hei conse a ion. The non-in asi e
mic oscale analysis used in his wo k in ol ed imaging, using op ical and elec on mic oscopy, and o
pigmen iden i ica ion, scanning elec on mic oscopy wi h ene gy dispe si e X- ay spec oscopy (SEM-EDS)
and Raman mic o-spec oscopy we e used. Mic o-des uc i e echniques such as HPLC-DAD and GC-MS
con ibu ed o he iden i ica ion o o ganic compounds and he cha ac e iza ion o he pain ing echnique.
2. Expe imen al
2.1. Pain ing samples
Eigh mic osamples we e ex ac ed wi h a scalpel om colou ed a eas o he o me pain ed al a piece
p esen behind he ac ual wooden al a piece o he chu ch o Cu ahua a de Ca angas (samples CCG14 -
CCG21) (Fig. 1). The loca ion o he samples and hei colou s is shown in Table 1. F agmen s o samples
wi h an a ea o less han 1 mm2 we e embedded in o an ac ylic anspa en esin Subi on® (Buenos Ai es,
A gen ina) and polished wi h sandpape o dec easing size (un il o 12.000 mesh) o p epa e he c oss-
sec ions (Fig.1).
2.2. Ins umen al and me hodology
Op ical Mic oscopy (OM)
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Obse a ion and pho og aphy o he su ace and c oss-sec ion o he samples was achie ed using a Leica
MZ6 s e eomic oscope and a Leica DM 750 mic oscope equipped wi h isible and ul a iole ligh sou ces in
no mal and pola ized modes.
Scanning elec on mic oscopy wi h ene gy-dispe si e X- ay spec oscopy (SEM-EDS)
SEM analysis by seconda y elec ons (SE) and backsca e ed elec ons (BSE) we e ca ied ou using a Field
En i onmen al Scanning Elec on Mic oscope Zeiss Sup a 40 coupled wi h an EDS mic oanalysis INCA X
Sigh , Ox o d Ins umen . Analyses we e ca ied ou using an accele a ed po en ial o 20 kV. C oss-sec ions
o he samples we e coa ed by spu e ing wi h a hin (less han 80 Ẳ) laye o pla inum. Se e al
measu emen s we e pe o med on selec ed a eas o ce ain g ains o each laye o he samples.
Mic o-Raman spec oscopy
Raman spec a o he c oss-sec ions we e acqui ed by a Renishaw InVia Raman con ocal spec ome e ,
coupled o a Leica DMLM mic oscope using a 532 and a 785 nm diode pumped solid s a e Nd:YAG
exci a ion lase sou ce. The spec a we e acqui ed wi h he Leica 50X N Plan (0.75 NA) lens wi h a 2 μm
spa ial esolu ion and he Olympus 100X (0.8 NA). The minimum heo e ical spo diame e using he 532 nm
lase was, o he Leica 50X and Olympus 100X, 0.9 μm and 0.8 μm, espec i ely, while using he 785 nm
lase i was, o he Leica 50X and Olympus 100X, 1.7 μm and 1.1 μm, espec i ely. Addi ionally, o
isualiza ion and ocusing, Leica 5X N Plan (0.12 aNA) and a 20X N Plan EPI (0.40 NA) lens we e used. Fo
ocusing on and sea ching o poin s o in e es , he mic oscope employs a mo o ized s age (XYZ). The
powe applied was se a he sou ce a a maximum o 50 mW while on he sample i was always less han 20
mW. No mally, 10-300 scans, each las ing 1-20 s, we e accumula ed o achie e a sui able signal- o-noise
enhancemen a an ope a ing spec al esolu ion o ≤1 cm-1. Spec a we e acqui ed be ween 150 and 3200
cm-1. S eam Line echnology was employed o gene a e high-de ini ion molecula images o speci ic
samples. B ie ly, he mo o ized s age o he mic oscope coupled o he Raman spec ome e mo es he
sample benea h he lens so ha he line o lase -ligh is as e ed ac oss he a ea unde analysis. A e wa ds,
om he collec ed spec a, chemical images a e gene a ed by conside ing he posi ion o main band o he
compound o in e es . In bo h cases, he Renishaw Wi e 3.2 (Renishaw, UK) so wa e was used o da a
collec ion and analysis.
High pe o mance liquid ch oma og aphy wi h diode a ay de ec o (HPLC-DAD)
HPLC–DAD analysis was ca ied ou wi h a Gilson 506C HPLC sys em using a Phenomenex Gemini 5μ
column (25 cm leng h, 4.6 mm in e nal diame e ). G adien elu ion was pe o med using mix u es o MeOH
and 1% ( / ) aqueous o hophospho ic acid, as desc ibed elsewhe e [34]. The de ec ion wa eleng h was
540 nm. A g ain om sample CCG19 and a ca mine lake s anda d (Ca mine Nacca a 42100, K eme
Pigmen e, Ge many) we e hyd olyzed in acidic me hanol as epo ed p e iously [28].
Gas ch oma og aphy coupled wi h mass spec ome y (GC–MS)
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Samples we e ex ac ed wi h ammonia 2.5 M and chlo o o m o sepa a e p o eins (ammonia phase) om
lipids (chlo o o m phase), as epo ed p e iously [2]. Fa y acids we e de i a ised as hei me hyl es e s
(FAME) [46] and analyzed by GC–MS, as desc ibed be o e [2]. T ime hylsilyl s e ol de i a i es we e
p epa ed and analyzed by GC–MS as epo ed in Lan os e al. [47]. Mass spec a o s e ols we e measu ed
in he selec ed ion moni o ing (SIM) mode wi h ions a m/z 129, 329, 368, and 458 o choles e ol. Amino
acid de i a i es we e p epa ed ollowing he p ocedu e o Be sani e al. [48] and analyzed by GC-MS, as
desc ibed in li e a u e [2].
3. Resul s and discussion
3.1 C oss-sec ion analysis by mapping
Blue sample and g ound laye
The blue sample (CCG14) aken om he Vi gin man le (Table 1) showed mos ly Cu in he SEM-EDS
mapping o he s a ig aphy. In addi ion, mino elemen s such as S, Si, Ca and Al sugges ed he p esence o
a coppe pigmen , likely azu i e (Cu3(CO3)2(OH)2) (Fig.2). Un o una ely, ca bon signal o he pigmen would
be o e lapped by he ca bon signal coming om he binde . Ce ain g eenish c ys alline zones a he OM
showed anadium con en , and a punc ual EDS analysis yielded highe amoun s o Cu, Pb and V and lowe
amoun s o As, Fe, Ca, Mg, Al, Si and Cl.
Figu e 3 shows he images ob ained om he Raman spec oscopy mapping by using he 532 nm lase ,
showing he p esence o azu i e in mos o he bluish c ys als on he su ace, bu also mo ami e, in he
g een c ys als, co esponding o a basic anada e o coppe and lead (PbCu(VO4)) ha is dispe sed on he
su ace. Addi ionally, hema i e (Fe2O3) and ana ase (TiO2) we e iden i ied by Raman spec oscopy, in
acco dance wi h he mino p esence o elemen s such as Fe, Ti, e c. Mo ami e is a anada e mine al o he
descloizi e g oup ha may be associa ed wi h azu i e in he Andean a ea, whose s uc u e o ms a se ies
wi h du i e (PbCuAsO4(OH)), in which anadium is eplaced by a senic [49], an elemen ha also appea s as
a ace elemen in he pic o ial laye . The Raman spec a a 532 nm o he mine als p esen in bo h he
pic o ial laye and he p epa a ion laye a e shown in Figu e 4. Spec a eco ded on he pic o ial laye
showed Raman bands a 180, 238, 333, 401, 541, 764, 840, 1096, 1430 and 1578 cm-1 cha ac e is ics o
azu i e [50,51]. In addi ion, he spec um o hema i e (Fig. 4a) shows a band p o ile compa ible wi h a na u al
o igin [52,53].
Figu e 4b shows he Raman spec a o mo ami e ob ained wi h 532 and 785 nm lase sou ces wi h main
bands a 113, 293, 333, 366, 617, 714, 804 and 828 cm-1 [54]. The he e ogenei y o he pic o ial laye o
azu i e sugges s a na u al o igin, bu also a local one conside ing he p esence o he mine als desc ibed
abo e. To ou knowledge, his is he i s ime epo ing he p esence o mo ami e as a mino mine al in a
blue pain laye o azu i e.
On he o he hand, Figu e 4a shows he main Raman bands o anhyd i e, mos ly in i s ype I (cubic)
polymo ph [55] in he g ound laye , which is consis en wi h he p esence o he CaSO4.xH2O sys em al eady
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obse ed in o he mu al pain ings whe e he use o a local mine al mix u e is p oposed [1,3]. In addi ion, a
mino p esence o clay componen elemen s such as Si, Al, K and Mg is obse ed a he g ound laye o all
samples, showing he he e ogenei y o he mix u e.
G een sample
The c oss-sec ion o he g een sample (CCG15) showed a pic o ial laye composed mainly o Cu acco ding
o he SEM-EDS analysis, bu in ce ain c ys als i is accompanied by S and Cl (Table 1). The SEM-EDS
mapping image clea ly shows ha hese elemen s a e ound in di e en c ys als associa ed wi h coppe (Fig.
5).
Two g een coppe -based mine als, a acami e [Cu2Cl(OH)3] and an le i e [Cu3SO4(OH)4], we e iden i ied om
he image ob ained om he Raman mappings (Fig. 6) by selec ing he main Raman band o each
compound. This indica es he use o a mix u e o g een pigmen s ha had been cha ac e ised sepa a ely in a
wooden sculp u e [20] and in a mu al pain ing [2,3], bu had ne e been ound oge he un il now.
The Raman spec a o each mine al (Fig. 4c) show bands a 226, 357, 452, 516, 821, 912 and 976 cm-1 o
a acami e [20,56] and bands a 269, 418, 989 and 1077 cm-1 o an le i e [2,3,57]. Fo he an le i e
iden i ica ion, he possible he mal decomposi ion o he mine al unde he lase beam, p e iously obse ed,
was conside ed, so he powe and ime o measu emen we e con olled o a oid such decomposi ion [3].
Flesh colou sample
SEM-EDS mapping o he lesh o he Child´s leg sample (sample CCG16), shows he con en o Pb and Hg,
p obably a mix u e o ed cinnaba o e million [HgS] wi h lead whi e (albayalde) [Pb3(CO3)2(OH)2], which is
o be expec ed o lesh o ha pe iod (Fig. 7). Howe e , i is obse ed in he images o he Raman mapping
in igu e 8, ha in he a ea whe e only lead is ound, he e is a mix u e o ce ussi e [PbCO3] wi h he
cha ac e is ic band a 1054 cm-1 [58] and minimum [Pb3O4], wi h bands a 227, 314, 478 and 551 cm-1 [59]
(Fig S1). In addi ion, he p esence o cinnaba (o e milion) is con i med by he Raman bands a 108, 255,
280, 289, 343 and 352 cm-1 [60] (spec um no shown). This mix u e o e milion and minium has no been
ound in o he mu als in he egion and could ha e been missed wi hou Raman mapping.
O ange sample
SEM-EDS mapping o he o ange sample CCG20 only iden i ied lead as he ch omopho e elemen (Table 1).
Raman spec oscopy analysis (Fig.S2) shows he p esence o wo lead compounds, he ed minium [Pb3O4],
wi h bands a 124 and 551 cm-1 [59] and massico , a yellow lead oxide [PbO], wi h bands a 142, 289 and
392 cm-1 [61]. Raman mapping yielded he images in igu e 9, which show he mix u e o pigmen s
dis ibu ed in he pic o ial laye . This combina ion o pigmen s has no been iden i ied in Colonial Andean
mu als in he egion un il now.
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Table
Table 1. Lis o samples, colou , loca ion, and esul s o SEM-EDS analysis on he pic o ial laye s o he
c oss-sec ions o he wall pain ing samples. Majo elemen s a e ma ked in bold s yle. The elemen s a ace
le els a e shown be ween pa en hesis.
Table (Supplemen a y Ma e ial)
Table 1S. Rela i e amino acid composi ion (in pe cen ages) o samples CCG15 and CCG21.
Sample Loca ion Colou Elemen s o he pic o ial laye
CCG14 Vi
g
in man le Blue Cu, S, Si, Ca, Al
(
V, Pb, Ti, As, Fe, K, M
g)
CCG15 Table G een Cu, S, Cl, Si, Al, Ca
(
Fe, K, M
g)
CCG16 Child's le
g
Flesh Pb, Ca, S, Al,
(
H
g
, Fe, K, M
g
, Na
)
CCG17 Child clo h Whi e Pb, Ca, S, Al,
(
Fe, K, M
g
, Na
)
CCG18 Man's cape Yellow As, S, Ca, Fe, Si
(
K, Al, M
g
, Na
)
CCG19 Cu ain Red N, P, Na, Al, S, Ca, K
(
M
g
, Si, Cl
)
CCG20 Man behind i
g
in O an
g
e Pb, S, Ca, Si, Al
(
Fe, K, M
g)
CCG21 F ame Black Si, Ca, Al, Fe, Na, M
g
, S, Cl
Sample Ala Gl
y
Th
Se
V
al Leu Ile P o H
y
p Asp Glu Phe
CCG15 6.8 12.5 5.5 9.2 12.5 5.9 0.9 7.8 2.5 16.6 14.8 5.0
CCG21 10.9 19.1 4.7 4.8 4.9 6.0 0.7 12.9 10.3 7.6 13.8 4.3

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Figu e Cap ions
Figu e 1. Image o he mu al pain ings ound behind he al a piece in he chu ch o Cu ahua a de Ca angas.
(Ph. Gab iela Si acusano) and c oss-sec ion o he samples.
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Figu e 2. a) BSE mic og aph, b) s e eoscopic image, c) MO image o an a ea o he c oss-sec ion o sample
CCG14 and d) mapping o coppe (Cu), anadium (V), silicon (Si), aluminium (Al), sul u (S), calcium (Ca).
Figu e 3. Raman mapping image o he pic o ial laye o he s a ig aphy o he blue sample CCG14.
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Figu e 4. Raman spec a o he blue sample CCG14. a) azu i e and hema i e (pic o ial laye ) and gypsum
(g ound laye ) a 532 nm, and b) mo ami e a 532 nm and 785 nm (pic o ial laye ). d) Raman spec a o he
g een mine als iden i ied in sample CCG15 a 532 nm.
Figu e 5. a) BSE mic og aph, b) s e eoscopic image o an a ea o he c oss-sec ion o he g een sample
CCG15 and mapping o coppe (Cu), calcium (Ca), chlo ine (Cl) and sul u (S).
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F igu e 6. Raman mapping image o he pic o ial laye in he c oss-sec ion o he g een sample CCG15
(Magni ica ion 100X). a) C oss-sec ion, b) an le i e and c) a acami e Raman mapping images.
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Figu e 7. a) BSE mic og aph o he c oss-sec ion o he lesh sample CCG16 and b) de ail o he mapped
zone. c) Mapping o lead (Pb) and d) me cu y (Hg).

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Figu e 8. Raman mapping image o he pic o ial laye in he c oss-sec ion o he lesh sample CCG16
(Magni ica ion 100X). a) C oss-sec ion, b) cinnaba c) lead whi e and d) minimum.
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Figu e 9. Raman mapping image o he pic o ial laye in he c oss-sec ion o he o ange sample CCG20.
(Magni ica ion 100X). a) C oss-sec ion, b) minium and c) massico .
Figu e Cap ions (Supplemen a y Ma e ial)
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Figu e S1. Raman spec a o he lead-con aining mine als iden i ied in he lesh sample CCG16 a 532 nm.
Figu e S2. Raman spec a o he lead-con aining mine als iden i ied in he o ange sample CCG20 a 785
nm.
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Figu e S3. HPLC ch oma og am o hyd olysed sample CCG19 a 540 nm and UV spec um o he peak a
13.8 min.
Figu e S4. Raman spec a o he mine als iden i ied in he a) whi e sample CCG17, b) yellow sample
CCG18 and c) black sample CCG 21.