Spear wattle

Scientific name

Acacia rhodoxylon. Family: Leguminosae.

Local names

Brown spearwood, rosewood.

Description and natural occurrence

A small tree attaining a height of 10 to 15 m and a stem diameter of 15 to 25 cm. The stem and branches are often fluted. Bark is dark in colour and shed in curly flakes.

Spear wattle is found in coastal and subcoastal parts of Central Queensland from near Eidsvold, north to south-east of Mt Garnet.

Wood appearance

Colour. The heartwood ranges from deep red-brown to dark brown. Sapwood is cream to white.

Grain. A straight grained wood. Sometimes presence of interlocked or wavy grain gives a ´ring´ feature to polished surfaces.

Texture. Very fine, even texture.

Wood properties

Density. 1280 kg/m3 at 12% moisture content; approximately 0.75 m3 of seasoned sawn timber per tonne.

Strength groups. (S1) unseasoned; (SD1) seasoned (brackets indicate provisional value).

Stress grades. F14, F17, F22, F27 (unseasoned), F22, F27, F34 (seasoned), when visually stress graded in accordance with AS 2082-1979, Visually stress-graded hardwood for structural purposes.

Joint groups. JD1 seasoned.

Shrinkage to 12% moisture content. Not available.

Unit shrinkage. Not available.

Durability above-ground. Class 1 - life expectancy over 40 years.

Durability in-ground. Class 1 - life expectancy over 25 years.

Lyctine susceptibility. Untreated sapwood susceptible to lyctid borer attack.

Termite resistance. Not resistant.

Preservation. Sapwood readily accepts preservative impregnation but penetration of heartwood is negligible using currently available commercial processes.

Seasoning. Dries slowly with little degrade.

Hardness. Very hard (rated 1 on a 6 class scale) in relation to indentation and ease of working with hand tools.

Machining. With appropriate tooling and feed speeds, spear wattle dresses and machines well, resulting in a fine polish.

Fixing. Wood is somewhat fissile, so care should be exercised with the use of standard fittings and fastenings.

Gluing. As with most high-density species, machining and surface preparation should be done immediately before gluing.

Finishing. Will readily accept paint, stain and polish.

Uses

Engineering and construction. Has been used extensively for fence posts. While strong enough for other construction purposes, this timber is not generally available in sizes suitable for engineered applications. Additionally, it is more suited to the applications below.

Decorative. Fancy turnery, walking sticks, ´ringed´ timber especially prized.

Others. Resonating parts of xylophones. Fingerboards and chin rests for violins (a substitute for ebony). Straight-grained timber may be used for sporting goods. Has future potential in ´small volume high value´ niche markets.

Identification features

General characteristics

Sapwood. Cream, distinct from heartwood.

Heartwood. Deep red-brown to dark brown.

Wood structure

Vessels. Solitary arrangement. Small, indistinct to the naked eye. Moderately numerous (4-12 per mm2).

Vessel lines. Fine, indistinct.

Parenchyma. Indistinct under a lens.

Rays. Fine, barely visible with a lens.

Other features

Burning splinter test. A match size splinter burns slowly with a small, steady flame. The ember glows for a long time, leaving a charcoal tip with a wispy white ash when extinguished.

Further reading

Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, 'Forest trees of Australia', 5th edn, CSIRO Publishing, Collingwood Australia.

Bootle, K 2005, 'Wood in Australia: types, properties and uses', 2nd edn, McGraw-Hill, Sydney.

Hopewell, G (ed.) 2006, 'Construction timbers in Queensland: properties and specifications for satisfactory performance of construction timbers in Queensland, Class 1 and Class 10 buildings', books 1 and 2, Department of Primary Industries and Fisheries, Brisbane.

Ilic, J 1991, 'CSIRO atlas of hardwoods', Crawford House Press, Bathurst, Australia.

Standards Australia, 2000, 'AS 2082-2000: Timber - hardwood - visually stress-graded for structural purposes', Standards Australia.

Last updated 10 August 2010