Toki Stone Selection

The stones chosen for Toki in Aotearoa were specifically selected for their toughness, hardness, and workability. Among the most favoured sources were Motutapu greywacke, Tahanga basalt, Nelson/D’Urville Island metasomatized argillite, Southland/Murihiku argillite, and Pounamu.

Due to its origin from the continental crust, Aotearoa had more diverse stone sources than those used for toki manufacture in the Pacific. A range of igneous (volcanic), metamorphic, and sedimentary rocks were available. In most Pacific locations, only one type of rock was available. Due to the variety of stone available, and each stone’s unique properties, Aotearoa had a diverse array of toki.

Stone selection – what makes a good stone for toki manufacture?

Archaeological experiments by Marianne Turner (2000:30-31) have indicated that toki stones were selected for the following properties:

- Toughness: Toki made from tough stone were resistant to breakage. They could be used for heavy forceful tasks and would last a long time without breaking. This meant that they did not have to be replaced or repaired often. The downside of tough stone is that flaking requires greater force and greater skill to remove high-angle flakes without fracturing the blank during late-stage manufacture.

- Hardness: Toki made from hard stone were resistant to abrasion. They would maintain a sharp edge over time, were useful for fine wood-cutting tasks and were resistant to damage. However, hard stones take longer to work, particularly during grinding and hammer dressing stages.

- Workability: how easy it is to create a toki from the stone. Different stone properties will affect the use of flaking, hammer dressing and grinding methods. These include the shape of the toki blank, how symmetrical the proportions are and how easy it will be to create a finished toki from the blank. Additionally, how easy the shape of the toki blank allows the placement of platforms for flaking on the blank surface. If the blank surface is too irregular, or alternatively too smooth, it will be difficult to establish flaking platforms.

- Homogeneity: The ability to fracture a stone and remove flakes depends on how similar the grain sizes within a stone are to one another. If the grain sizes are quite similar to one another (homogenous), it is more likely that flakes can be removed in a predictable pattern and the toki blank will not break during manufacture.

- Grain size: The size of the grains and how close they are to one another, which determines the stone's hardness, toughness and resistance to fracture. Fine-grained stones were easier to flake than coarser-grained stones, as they are harder. It would take a long time to hammer dress a fine-grained rock. Coarser-grained stones are softer than fine-grained rocks and are easier to hammer dress and grind and harder to flake. This is because the grains are less closely packed together than fine-grained rocks (Turner 2000:31, 34).

^{[Carved adze handle - carved by Nutana], PH-1991-12-B7090. Thomas William George Howard Hammond Collection, Cultural permissions apply.}

Major sources of toki stone found in Aotearoa New Zealand

Major toki stone sources:

Motutapu greywacke is a fine to coarse-grained sedimentary rock from Motutapu Island:

- It is characterised by a green colour, which is variable in intensity across the surface of the rock. This variation in surface colour is particularly recognisable when the stone is polished.

- Fine-grained Motutapu greywacke is good quality for toki manufacture.

- It is very hard, much harder than Tahanga basalt, meaning it is highly resistant to abrasion (such as cutting edge damage). However, it is much less tough than Tahanga basalt – it is brittle. This means that during the flaking process, the hammer blows must be controlled so as not to fracture the blank; similarly, the tool risks fracture if used in high-impact tasks.

Tahanga basalt is a fine-grained volcanic rock sourced from Tahanga, a hill above Opito Bay, Coromandel:

- It ranges in colour from medium to dark grey.

- Tahanga basalt was a very tough stone and could be flaked to make quadrangular cross-sectioned toki.

- Toki were roughed out at the quarry with water-rolled hammer stones made from basalt and andesite gathered from the nearby beach.

- They were then transported to other nearby locations for the final, more precise and meticulous high-angled shaping.

- Tahanga basalt was not hard as Nelson/Marlborough argillite, which means that it was more difficult to achieve very sharp high-angled edges using flaking techniques, but comparatively more easily hammerdressed and ground.

- As a volcanic rock with high iron content, it can be distinguished from other rocks by a magnet.

Nelson/D’Urville Island metasomatized argillite is found within the Nelson mineral belt, which includes D'Urville Island.

- The argillite found in the region ranges from light grey to dark grey.

- Some D'Urville Island argillite has distinctive fine veining, which the mainland Marlborough argillite does not have. This D’Urville Island veined argillite may be light grey to light blue or green with fine black veins; dark black with fine veins or dark green grey with fine veins.

- This argillite is characterised by fine-grained, tough, hard stone, which was able to be flaked to a high, sharp edge angle.

- Toki produced from this stone were highly resistant to breakage and abrasion, however, manufacture required high skill and time investment. The toughness and hardness of the stone meant that flaking techniques were preferential, and that hammer dressing and grinding techniques took a long time.

Glossy when polished.

Southland/Murihiku argillite. This stone can be found at Riverton beach, as well as Colyer's and Tikore Islands.

- Riverton argillite is light green. Bluff Harbour argillite is dark grey-green.

The grain size ranges from fine to coarse.

- This argillite was difficult to work. Archaeological evidence shows that it was extensively hammer dressed. It was used for a range of large quadrilateral and triangular cross-sectional toki suitable for canoe manufacture. The types of toki produced required high skill. The toki are found throughout the lower South Island.

Pounamu (specifically nephrite) from the West coast.

- Ranges in colour from light to dark green.

- Manufactured into toki by hammerstone, sawing and grinding techniques.

- Harder and tougher than Nelson/D’Urville Island argillite.

- Highly glossy when polished.

Name	Type of stone	Classification	Grain size	Raw stone colour	How to tell it apart from other stones
Motutapu Greywacke	Greywacke	Sedimentary	Fine to coarse	Green, variable in intensity across the surface of the rock.	Surface colour variation is particularly noticeable when polished. Does not become glossy when polished. Not magnetic.
Tahanga Basalt	Basalt	Igneous	Fine	Medium grey to dark grey, but can weather to lighter grey	Tahanga basalt and Nelson argillite look similar as unpolished raw material. Can be distinguished from argillite by a magnet, as it has a high iron content due to its volcanic origin. Difficult to create high, sharp edge angles found in Nelson argillite toki, so Tahanga basalt toki may have more rounded edges than argillite toki due to the manufacturing techniques.
Nelson/D'Urville Island Argillite	Metasomatised argillite	Metasedimentary	Fine	Marlborough region argillite ranges in appearance from: light grey to dark grey. A distinctive feature of some D'Urville Island argillite is fine veins.	Not magnetic. Looks glossy when polished.
Pounamu (specifically, nephrite)	Pounamu (nephrite)	Metamorphic	Fine	Green to dark green	Highly glossy when polished. Colour.
Southland/ Murihiku Argillite	Argillite	Metasedimentary	Fine to coarse	Riverton argillite is light green. Bluff Harbour argillite is dark grey-green.

Bibliography

[1] Turner, M., 2000. The Function, Design and Distribution of New Zealand Adzes. Unpublished PhD thesis, Anthropology, University of Auckland