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Australian blackwood (Acacia melanoxylon)

Australian blackwood (Acacia melanoxylon)

Common Name(s): Australian blackwood, Tasmanian blackwood, Acacia blackwood

Scientific Name: Acacia melanoxylon

Distribution: Native to Tasmania and eastern Australia; also introduced to Africa, South America, and southern Asia

Tree Size: 65-100 ft (20-30 m) tall,

                 2-3 ft (.6-1.0 m) trunk diameter

Average Dried Weight: 40 lbs/ft3 (640 kg/m3)

Specific Gravity (Basic, 12% MC): .54, .64

Janka Hardness: 1,160 lbf (5,180 N)

Modulus of Rupture: 15,020 lbf/in2 (103.6 MPa)

Elastic Modulus: 2,148,000 lbf/in2 (14.82 GPa)

Crushing Strength: 5,950 lbf/in2 (41.0 MPa)

Shrinkage: Radial: 3.9%, Tangential: 7.9%,

                  Volumetric: 11.9%, T/R Ratio: 2.0

Color/Appearance: Color can be highly variable, but tends to be medium golden or reddish brown, similar to Koa or Mahogany. There are usually contrasting bands of color in the growth rings, and it is not uncommon to see boards with ribbon-like streaks of color. Boards figured with wavy and/or curly grain are also not uncommon.

Grain/Texture: Grain is usually straight to slightly interlocked, and sometimes wavy. Uniform fine to medium texture.

Endgrain: Diffuse-porous; large pores in no specific arrangement; few to very few; solitary and radial multiples of 2-3; narrow rays, spacing normal, can be reddish color; parenchyma vasicentric.

Rot Resistance: Rated as moderately durable regarding decay resistance, though susceptible to insect attack.

Workability: Australian Blackwood is easily worked with both hand and machine tools, though figured wood and pieces with interlocked grain can cause tearout. Australian Blackwood turns, glues, stains, and finishes well. Responds well to steam bending.

Odor: No characteristic odor.

Allergies/Toxicity: Although severe reactions are quite uncommon, Australian Blackwood has been reported as a sensitizer. Usually most common reactions simply include eye, skin, and respiratory irritation, as well as asthma-like symptoms. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.

Pricing/Availability: Although Australian Blackwood is considered an invasive species and a pest in some areas, the lumber is still fairly expensive, and figured wood is even costlier. It has been used as a lower-cost alternative to Hawaiian Koa.

Sustainability: This wood species is not listed in the CITES Appendices or on the IUCN Red List of Threatened Species.

Common Uses: Veneer, furniture, cabinetry, musical instruments, gunstocks, turned objects, and other specialty wood objects.

Comments: Although called “Blackwood,” the name is somewhat of a misnomer, as its wood is not at all black. Rather, its lustrous golden brown grain has been used as a sustainable alternative to Koa. The species has been introduced to a number of regions worldwide—either as an ornamental shade tree, or on a plantation for lumber—and in many areas, the hardy tree species has become an invasive species.

Australian Blackwood compares very closely with Koa. Australian Blackwood tends to have a straighter grain, and  slightly better machining characteristics than Koa.

Images: Drag the slider up/down to toggle between raw and finished wood. A special thanks to Steve Earis for providing a wood (veneer) sample of this wood species.

[caption id="attachment_22091" align="alignleft" width="300"]Australian blackwood (Acacia melanoxylon) Australian blackwood (Acacia melanoxylon)[/caption]

Identification: See the article on Hardwood Anatomy for definitions of endgrain features.

Australian blackwood (endgrain 10x)

Australian blackwood (endgrain 10x)

Australian blackwood (endgrain 1x)

Australian blackwood (endgrain 1x)

Porosity: diffuse porous

Arrangement: solitary and radial multiples

Vessels: large, few to very few

Parenchyma: vasicentric

Rays: narrow, normal spacing; can be reddish color that blends in with wood fibers

Lookalikes/Substitutes: Hawaiian koa (Acacia koa) is anatomically indistinguishable from Australian blackwood, at least on a macroscopic level. (When viewed under microscope, about 50% of the rays in koa are uniseriate, while Australian blackwood’s rays are only about 20% uniseriate.)

Notes: Heartwood fluoresces under blacklight.

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