Pottery production in salt workshops: petrographic and XRF analyses of pottery from Nueva Esperanza, El Salvador

Figures & data

Figure 1. Map of (a) site locations and (b) geographic map (adopted from Lexa et al. 2011).

Figure 2. Sections of excavated areas from the 2014 field season.

Figure 3. Investigated samples from Nueva Esperanza.

Table 1. Sample descriptions.

No.	Material	Ware	Vessel Form	Slip	Decoration	Layer
1	Potsherd	Coarse	Type B	-	-	22 (7.5 YR 3/1)
2	Potsherd	Coarse	Type A	-	-	22 (7.5 YR 3/1)
3	Potsherd	Coarse	Type C	-	-	22 (7.5 YR 3/1)
4	Potsherd	Fine	Jar	Black-brown	-	22 (7.5 YR 3/1)
5	Potsherd	Fine	Bowl	Orange on cream	Usulután and red paint	22 (7.5 YR 3/1)
6	Potsherd	Fine	Bowl	Orange on cream	Groove	22 (7.5 YR 3/1)
7	Potsherd	Coarse	Type A	-	-	30 (10 YR 3/2)
8	Potsherd	Coarse	Type B	-	-	30 (10 YR 3/2)
9	Potsherd	Coarse	Type C	-	-	30 (10 YR 3/2)
10	Potsherd	Fine	Bowl	Orange	Usulután	30 (10 YR 3/2)
11	Potsherd	Fine	Bowl	Orange	-	30 (10 YR 3/2)
12	Potsherd	Coarse	Type A	-	-	31 (10 YR 2/3)
13	Potsherd	Coarse	Type B	-	-	31 (10 YR 2/3)
14	Potsherd	Coarse	Type C	-	-	31 (10 YR 2/3)
15	Potsherd	Fine	Bowl	Orange on cream	Usulután	31 (10 YR 2/3)
16	Potsherd	Fine	Bowl	Red	-	31 (10 YR 2/3)
17	ACL	-	-	-	-	22 (7.5 YR 3/1)
18	ACL	-	-	-	-	30 (10 YR 3/2)
19	ACL	-	-	-	-	31 (10 YR 2/3)

*Type A is convergent body, Type B is divergent body, Type C is direct body.

*ACL is amorphous clay lumps.

Figure 4. Thin-section photomicrographs of samples from Nueva Esperanza taken via plane-polarized light (PPL) and cross-polarized light (XP) qz: quartz; pl: plasioclase; ho: amphibole; opx: orthopyroxene; cpx: clinopyroxene; tu: tuff; vo: volcanic rock; hyp: hypabyssal rock

Table 2. Mineral composition proportions revealed via petrographic analysis.

No.	qz	pl	K-fel	bt	lm	mv	hb	opx	cpx	ol	cm	vg/tu	vo	plu	hyp
1	35	145	5	0	19	0	1	3	1	3	9	8	31	2	0
2	43	134	19	0	14	0	0	3	1	0	9	10	23	1	43
3	35	109	39	3	13	0	0	0	0	0	4	10	43	0	44
4	47	97	23	1	11	0	1	3	2	0	5	45	33	0	32
5	18	164	24	0	14	0	3	5	9	0	2	25	33	0	3
6	33	123	20	0	58	0	1	5	5	1	0	37	11	0	6
7	52	109	50	1	5	0	1	1	3	0	2	23	16	0	37
8	42	111	37	1	7	0	0	1	1	0	0	27	22	2	49
9	54	105	38	0	9	0	0	0	1	0	0	0	2	18	43
10	31	88	71	0	19	0	0	0	3	0	6	39	17	0	26
11	15	145	23	0	9	0	0	12	4	0	6	13	70	0	3
12	20	133	35	0	5	0	1	5	6	0	2	10	35	2	46
13	23	132	38	0	4	0	1	1	0	0	0	5	30	0	66
14	34	123	40	0	7	0	3	3	2	0	2	10	9	2	65
15	20	152	44	0	8	0	0	1	2	0	2	23	47	1	0
16	51	113	42	2	10	0	1	1	6	0	5	15	18	1	35
17	67	64	106	2	19	0	1	0	4	0	33	2	1	0	1
18	42	95	79	1	23	1	1	1	0	0	36	3	10	0	8
19	59	97	81	4	16	0	0	1	0	0	25	5	9	0	3

Notes: qz: quartz; pl: plasioclase, K-fel: Karl feldspar; bi: biotite; li: limonite; mv: muscovite; hb: hornblende; opx: orthopyroxene; cpx: clinopyroxene; ol: olivine; cm: colored minerals; vg/tu: volcanic glass/tuff; vo: volcanic rock; plu: plutonic rock; hyp: hypabyssal rock

Table 3. Petrographic analysis summary.

Group	Nueva Esperanza A	Nueva Esperanza B	Nueva Esperanza C-1	Nueva Esperanza C-2	Nueva Esperanza D
Samples	Nos. 5, 6, 11, 15	Nos. 4, 10, 16	Nos. 1, 2, 7, 12, 13	Nos. 3, 8, 9, 14	Nos. 17, 18, 19
Matrix	Orange-brown to dark reddish-brown, optically inactive, vitrified or weakly vitrified.	Dark reddish-brown, optically inactive, vitrified or weakly vitrified.	Orange-brown to dark reddish-brown, optically active, weakly inactive.	Orange-brown to dark reddish-brown, optically active, weakly inactive, weakly vitrified.	Orange-brown to dark reddish-brown, optically active.
Void	3–5%, consisting mainly of meso-elongate vughs and meso-planar voids. Moderate alignment of voids to margins of section. No. 11, consisting mainly of macro-elongate vughs and channels and macro-planar voids. Weak alignment of voids to margins of section.	3–5%, consisting mainly of meso-planar voids. Moderate alignment of voids to margins of section. No. 4, consisting mainly of meso-planar voids. Weak alignment of voids to margins of section.	5–15%, consisting mainly of macro-elongate vughs voids and meso-planar voids. Moderate alignment of voids to margins of section. No. 12, 35%, consisting mainly of macro-elongate vughs and channels. Moderate alignment of voids to margins of section.	7–10%, consisting mainly of macro-elongate vughs voids and meso-planar voids. Moderate alignment of voids to margins of section. No. 14; 5%. consisting mainly of meso-vughs, channels and meso-planar voids. Moderate alignment of voids to margins of section.	3%, consisting mainly of meso-vughs. No alignment of voids to margins of section.
General inclusion size	Significant variation, poorly sorted (No. 5 is weakly sorted), 0.15–0.8 mm, few 0.8–1.1 mm. No. 11, bimodal, 0.1–0.65 mm, few 0.7–1.1 mm	Poorly or moderately sorted, 0.15–0.6 mm, few 0.8–1.0 mm	Moderately sorted (No. 13, poorly sorted), 0.15–0.7 mm, few 0.9–1.2 mm	Moderately sorted, 0.2–0.8 mm, few 0.9–1.2 mm	Poorly sorted, 0.15–0.5 mm
Hypabyssal rock fragments	Rare weathered rock, sub-angular or sub-around rock (0.2–0.7 mm)	Dominant weathered rock sub-angular or sub-around rock (0.1–0.4 mm)	Dominant weathered plutonic rock, sub-angular or sub-around rock (0.3–0.75 mm)	Dominant weathered rock, sub-angular or sub-around rock (0.3–0.8 mm), few 0.9–1.2 mm	Frequent weathered rock, sub-angular or sub-around rock, 0.2–0.4 mm
Volcanic rock	Dominant, sub-angular or sub-around rock (0.1–0.75 mm, some 0.7–1.1 mm), basalt and andesite.	Dominant, sub-angular or sub-around rock (0.15–0.65 mm), basalt and andesite.	Dominant, sub-angular or sub-around rock (0.25–1.1 mm), basalt and andesite.	Dominant, sub-angular or sub-around rock (0.25–1.1 mm), basalt and andesite.	Rare, sub-angular or sub-around rock (0.1–0.3 mm), basalt and andesite.
Tuff	n/a	Frequent tuff (0.2–0.8 mm) and volcanic grass (0.1–0.2 mm)	n/a	Tuff (0.2–1.1 mm) and volcanic grass (0.1–0.2 mm)	Tuff (0.1–0.3 mm) and volcanic grass (0.1–0.3 mm)
Plagioclase	Frequent plagioclase, angular and sub-angular, 0.1–0.6 mm, several 1.1 mm	Frequent plagioclase, angular, and sub-angular, 0.1–0.5 mm	Frequent plagioclase, angular, and sub-angular, 0.2–0.7 mm	Frequent plagioclase, angular, and sub-angular, 0.25–0.85 mm	Dominant plagioclase, angular, and sub-angular, 0.15–0.5 mm
Quartz	Angular and sub-angular, 0.1–0.6 mm	Angular and sub-angular, 0.1–0.45 mm, few >1.0 mm	Angular and sub-angular, 0.2–0.85 mm	Angular and sub-angular, 0.2–0.8 mm	Angular and sub-angular, 0.1–0.5 mm
K-feldspar	Rare K-feldspar, sub-angular, sub-around, 0.1–0.8 mm,	Rare K-feldspar, sub-angular, sub-around, 0.1–0.7 mm,	Rare K-feldspar, sub-angular, sub-around, 0.2–0.8 mm, few 1.0–1.1 mm	Rare K-feldspar, sub-angular, sub-around, 0.2–0.7 mm	Common K-feldspar, sub-angular, sub-around, 0.1–0.25 mm
Pyroxene	Orthopyroxene (0.1–0.45 mm) and clinopyroxene (0.1–0.6 mm)	Rare clinopyroxene (0.1–0.7 mm), No. 16, rare orthopyroxene (<0.2 mm)	Orthopyroxene (0.1–0.45 mm) and clinopyroxene (0.1–0.4 mm)	Rare orthopyroxene (0.1–0.45 mm) and clinopyroxene (0.2–0.3 mm)	Rare orthopyroxene (0.1–0.4 mm) and clinopyroxene (0.1–0.2 mm)
Mica	No. 6, rare biotite, <0.5 mm	Rare biotite, <0.4 mm	Rare biotite, <0.5 mm	Rare biotite, <0.3 mm	Rare biotite, <0.3 mm
Amphibole	No. 5, rare hornblende, 0.15 mm	Rare hornblende, 0.1–0.4 mm	Rare hornblende, 0.1–0.3 mm	Rare hornblende, 0.1–0.3 mm	No. 18, rare biotite, <0.2 mm

Figure 5. Scatterplot of the principal component analysis conducted for the Nueva Esperanza samples.

Figure 6. Scatterplots of SiO₂-Al₂O₃ and CaO-K₂O for Nueva Esperanza samples.

Table 4. Major and minor elements found in Nueva Esperanza samples based on WD-XRF (wt.%).

No.	Na2O	MgO	Al2O3	SiO2	P2O5	K2O	CaO	TiO2	MnO	Fe2O3
1	2.7	2.3	18.2	59.6	0.2	1.3	2.9	1.0	0.3	11.1
2	2.6	1.9	18.3	60.0	0.3	1.4	2.8	1.0	0.3	11.2
3	2.9	2.2	19.1	59.8	0.4	1.6	2.6	1.0	0.1	10.0
4	2.4	1.9	19.3	58.7	0.3	1.8	2.6	1.1	0.3	11.4
5	1.9	2.3	23.2	51.8	0.3	0.7	4.0	1.1	0.3	14.0
6	1.9	1.4	25.9	49.2	0.5	1.0	2.1	1.4	0.2	16.1
7	3.1	4.6	17.4	58.2	0.1	1.2	3.3	1.0	0.4	10.5
8	2.5	2.5	17.8	61.0	0.2	1.8	3.0	0.9	0.2	9.9
9	2.4	3.7	18.0	59.4	0.1	1.9	2.8	0.9	0.2	10.2
10	2.6	1.8	18.7	60.2	0.1	1.7	2.9	1.1	0.2	10.5
11	2.3	3.3	23.7	49.1	0.2	0.8	4.2	1.2	0.3	14.5
12	3.0	3.5	18.2	58.0	0.1	1.5	2.6	1.0	0.4	11.5
13	3.3	3.1	18.1	59.8	0.1	1.3	3.0	1.0	0.4	9.6
14	3.0	3.6	17.7	59.0	0.1	1.6	2.8	0.9	0.3	10.8
15	1.8	2.6	24.2	49.3	0.1	0.6	4.1	1.3	0.2	15.5
16	2.4	2.2	18.9	60.6	0.1	1.8	2.2	1.0	0.2	10.3
17	3.3	2.7	17.1	62.6	0.2	2.5	2.6	0.8	0.2	7.7
18	2.8	2.1	18.1	62.4	0.1	2.1	2.3	1.0	0.2	8.6
19	3.3	2.6	17.9	61.2	0.1	2.1	2.5	0.9	0.1	8.8

Table 5. Trace elements found in Nueva Esperanza samples based on WD-XRF (ppm).

No.	Ni	Cu	Zn	Rb	Sr	Y	Zr	Ba	V	Cr
1	114	121	173	44	439	b.d.	176	1997	480	142
2	128	110	184	46	400	18	168	1229	375	62
3	133	131	181	56	395	b.d.	170	1192	372	133
4	158	117	216	47	320	13	200	1374	527	79
5	106	166	209	33	388	22	162	1240	675	81
6	116	216	218	33	344	11	157	1481	580	105
7	116	108	154	44	315	12	152	925	351	74
8	96	75	132	50	382	15	156	1861	384	73
9	113	57	167	38	354	18	140	1601	410	107
10	124	88	185	51	359	19	224	1130	452	205
11	119	128	213	26	469	16	115	1618	635	121
12	112	93	161	37	319	b.d.	139	1027	570	68
13	105	100	146	27	338	20	169	1129	540	124
14	105	74	126	44	339	20	144	1390	364	93
15	121	159	184	25	347	12	118	921	586	144
16	121	50	185	52	394	b.d.	271	1688	378	125
17	130	88	178	88	397	b.d.	231	1237	204	119
18	124	70	191	67	330	b.d.	274	1140	275	146
19	129	52	152	69	394	b.d.	272	1439	251	103

Lexa, Jaroslav, Jiři Šebesta, Jose Alexander Chavez, Walter Hernández, and Zoltán Pécskay. 2011. “Geology and Volcanic Evolution in the Southern Part of the San Salvador Metropolitan Area.” Journal of Geosciences 56 (1): 105–140. doi:https://doi.org/10.3190/jgeosci.088.

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Data availability statement

Excavated materials are available from the Dirección de Arqueología, Dirección Nacional del Patrimonio Cultural, Ministerio de Cultura, El Salvador. All digital and analysis data were generated by the authors and are available for research purposes by contacting the corresponding author.