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4. New Macroscopic Descriptions of 33 Stone Artefacts from Macau

The results of an initial macroscopic examination of archaeological stone from the Macau Museum Collection and the Hac Sa (1997) excavation are set out in Table 1 and Table 2. The more important artefacts are marked *.

Table 1: Macau Museum material examined during 2007
No. Museum catalogue number Implement typeMacroscopicdescription Comments
1 303.2/13 Struck flake Altered igneous, possibly porphyritic andesite or basalt Fine grained; splintery fracture; iron-stained; small angular inclusions
2 303.3/43 Possibly preform cutting tool or ring blank Quartz Massive, rounded end; possibly failed during manufacture; brittle.
3 303.1/44 Struck flake Altered quartz White/cream colour; flinty appearance; irregular fracture; has ring-making potential.
4 303.1/56 Possible preform cutting tool or ring blank Altered vein quartz Platey cleavage creates tabular fragments; iron stained; polished both sides (natural, not ground)
5* 303.3/59 Not a tool Altered microgranite. Pebble; fine-grained groundmass with feldspar laths and random scatter of dark opaque minerals, possibly iron-titanium oxides.
6 303.2/72 Adze Vein quartz Glassy appearance; massive quartz with secondary quartz intergrowths; unlikely texture for ring making
7 303.2/78 Struck flake - preform ring blank? Hydrothermally altered sercitized quartz with muscovite Recrystallised; hydrothermal mineralisation. Fracture-free. Suitable fabric and texture for ring making.
8 304.4/19 Not a tool Quartz Sub-angular pebble.
9 304.3/24 Broken pebble Indurated mudstone Iron-stained dark-grey pebble; siliceous veinlets; transverse fracture.
10 304.4/32 Not recorded Altered tuff Well-developed cleavage; banding; pale green colour weathering to brown
11 304.4/40 Broken pebble Microgranite Fractured at right angles to curved shaped edge
12 304.4/47Broken pebble Not recorded Fractured at right angles to curved shaped edge
13 304.4/50 Broken pebble Granite Shoulder; ground surface; broken at right angles to curved shaped edge
14 304.3/54 Ground pebble Tuffite Coarse-grained volcanic weathering to greenish brown colour; soft; similar to displayed adze (302.1 (95HST6); ground flat surface area
15 304.4/66 Not recorded Devitrified volcaniclastic Parallel sides; light weight; soft; pale buff-coloured.

Table 2: Material from the Hac Sa (1995) excavation
No. Museum catalogue number Implement type Macroscopic description Comments
1* 95HST 1 (Fig. 1) Stone ring grinding tool Iron-stained quartzite? Lemon-shaped with nipples at each end, one with highly polished rim, coloured green;
2* 95HST6 (Fig. 8) Ground unpolished adze Coarse grained porphyritic chloritic andesitic tuff Pale green colour; altered plagioclase phenocrysts with alteration rims; patches of oxidised iron mineral (limonite?); possible sub-angular volcaniclastic clasts; banding but no cleavage; work-worn butt; facetted sides.
3* 95HST7 302.10 Adze Hydrothermally altered granular quartz with sericite Produced by the hydrothermal alteration of feldspar in the host granite. Flaked; tough texture; fractured during manufacture and discarded.
4 95HST9A Possibly a preform cutting tool or ring blank Hydrothermally altered vein quartz with sericite Cryptocrystalline texture; iron-stained along fractures; one side is flat and other side is rounded. Struck pebble.
5 95HST15 Struck flake Massive strained quartz Bulb of percussion and step-fractures; superficial iron staining; not utilised as a tool.
695HST16 Struck flake Massive quartz Lacks bulb of percussion, sharp edges, unworked.
7 95H5T17 Struck pebble Strained cryptocrystalline quartz Brittle, tabular fracture,
8 95HST18 Preform cutting tool or ring blank Quartz Flakes detached from pebble to form cutting edge
9 95HST23 Preform cutting tool or ring blankQuartz Ground curved cutting edge; transverse fracture; brittle.
10 95HST25 Struck flake Massive quartz Sharp edges, unworked, iron stained.
11 95HST26 Possible preform tool or ring blank Vein quartz with secondary mineral inclusions Pecked to form curved blade-like profile but transverse fracture presumably occurred during shaping process. Modified pebble,
12 95HST28 Struck flake Vein quartz Chip detached from cobble
13 95HST40 Unworked pebble Strained massive quartz Iron-stained, natural tabulate fracture
14* 95HST56304.1 Not a tool Coarse-grained porphyritic chloritic tuff Iron-stained; differentially weathered; green coloured groundmass; angular and sub-angular fracture; siliceous/feldspathic inclusions;
15* 95HST61 Modified pebble Micaceous bedded metasediment Fine grained; green coloured; flaked parallel to strong cleavage; dark spotting micaceous; small corroded patches and intergrowths of pale-coloured altered feldspar; (naturally?) rounded end
16 95HST90 Possibly preform ring blank Recrystallised cryptocrystalline quartz Iron-stained, modified edge, bi-convex with flat edge, partly polished on both sides.
17* 95HST94 Failed preform tool? Altered quartz with secondary muscovite and chlorite Relict slikensliding producing stepped fracture; failed along mineralised veinlet; rounded pecked unground edge

The following discussion points arise from the information presented in Tables 1 and 2.

4.1 The choice of raw material

Figure 2
Figure 2: Coloane adze 33

Figure 3
Figure 3: Coloane adze 33 (reverse)

Figure 4
Figure 4: Coloane adze 33 (profile)

Figure 5
Figure 5: Coloane adze 33 (reverse profile)

Figure 6
Figure 6: Coloane adze 33 (section)

Figure 7
Figure 7: Coloane adze 33 (reverse section)

Figure 8
Figure 8: Adze made from andesitic tuff, found at Hac Sa

The makers of prehistoric stone rings were very selective in their choice of raw material. They seemed to prefer vein quartz, which had either been altered chemically by hydrothermal mineralisation and/or strained by tectonic action. Considering the occurrence of altered quartz excavated from the Hac Sa site:

  1. it was tougher, less brittle and probably more easily worked than the comparatively unaltered massive quartz available locally;
  2. the strained quartz possesses a natural tabular cleavage, well matched to the profile of ornamental rings;
  3. small gold-coloured flakes of sericite in the quartz may have enhanced the appearance, and added to the interest, of the ornaments;
  4. weaknesses in the mineral fabric would have been exposed during the weathering process of rock into pebbles. Therefore, a pebble that was fracture-free would be attractive for the manufacture of ornamental rings. By comparison, the risk of failure during the manufacturing process because of micro-fractures in the lithic material might reasonably be expected to increase for specimens that were quarried from outcrop, or utilised from cobbles and pebbles.

4.2 The archaeological stone

A microscopic examination of the rocks in polished thin section is necessary to confirm, or otherwise, the macroscopic descriptions provided in the Tables 1 and 2. Two categories of archaeological stone are represented in the examined material: mineral and stone. The mineral material was substantially quartz; the type of utilised stone material was more variable.

4.2 The worked quartz

  1. some items clearly are preform blanks for making ornamental rings;
  2. a new group of artefacts, which resemble preforms of small cutting tools, for example small adze or axe tools, is proposed. Variants of these possibly new tool forms might be recognised more widely in excavations around the Zhujiang estuary and beyond. However, there remains the possibility that the artefacts may represent an early stage in the manufacture of blanks for ring making.

4.3 The worked stone

  1. Most of the specimens of worked stone are mainly extrusive igneous, and may have their origin in the Zhujiang estuary or adjacent areas. Petrographic and geochemical evidence might be used to track these artefacts back to their sources (Davis et al. in prep). A search could be made at the outcrop sites for further evidence of prehistoric quarrying and tool manufacture in the Zhujiang estuary, for example Wong Tei Tung, Hong Kong (Davis and Ixer 2009).
  2. There is no clear evidence that the local granitic rock was favoured for the manufacture of axe and adze cutting tools (Figure 8). Overall, this observation accords with implement petrological evidence worldwide. A source of the rock used to manufacture the ring grinding and polishing tool (Figure 1) is thought unlikely to occur locally. However, pebbles of the finer grained igneous lithologies, which occur as pebbles and cobbles in beach deposits derived from dyke rock in the granite, may have been utilised for tool making. Petrographical and geochemical evidence should help to clarify this situation.

Stone tool No. 33 (Figures 2-7) was examined in addition to the items reported in Tables 1 and 2. This adze, which was donated by the finder to the Macau Museum but is not currently displayed, was a chance find in the area adjacent to the Hac Sa (South) excavation site. It is a good-quality ground and polished adze. Visually, the petrology of some adzes from Hong Kong, for example, adze No. 86 (Lo So Shang site 97), and adze No. 81 (Hai Dei Wan site 39), closely resemble this implement. Macroscopically, the rock is volcaniclastic, similar to a welded tuff.

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