Coolibah burl (Eucalyptus coolabah)

Common Name(s): Coolibah, coolabah

Scientific Name: Eucalyptus coolabah (E. microtheca and a number of less-common species are also considered coolibahs, see comments below)

Distribution: Eastern Australia

Tree Size: 20-30 ft (6-10 m) tall,

                     1-2 ft (.3-.6 m) trunk diameter

Average Dried Weight: 70.6 lbs/ft3 (1,130 kg/m3)

Specific Gravity (Basic, 12% MC): .98, 1.13

Janka Hardness: 3,730 lbf (16,590 N)

Modulus of Rupture: 20,960 lbf/in2 (144.5 MPa)

Elastic Modulus: 2,500,000 lbf/in2 (17.24 GPa)

Crushing Strength: 11,800 lbf/in2 (81.3 MPa)

Shrinkage: Radial: ~3%, Tangential: ~6%,

                          Volumetric: ~9%, T/R Ratio: ~2

Color/Appearance: Heartwood ranges from orangish pink to a much darker reddish brown. Thin sapwood is grayish white. Nearly always seen in burl form.

Grain/Texture: Grain is generally interlocked, with a fine texture.

Endgrain: No data available.

Rot Resistance: No data available.

Workability: No data available.

Odor: No characteristic odor.

Allergies/Toxicity: Although severe reactions are quite uncommon, coolibah has been reported to cause skin irritation. See the articles Wood Allergies and Toxicity and Wood Dust Safety for more information.

Pricing/Availability: Almost without exception sold as burl caps or blanks. Prices are very high, on par with most other imported Australian burls.

Sustainability: Coolibah is not listed in the CITES Appendices, but is reported by the IUCN as being near threatened (for E. coolabah only). Technically it doesn’t meet the Red List criteria of a vulnerable or endangered species, but is close to qualifying and/or may qualify in the near future.

Common Uses: Turned objects, knife and gun grips, inlay, and other small specialty items.

Comments: The name coolibah comes from the name gulabaa given to the tree by indigenous Australians. The coolibah trees known today encompass several different species, but when it was first described in 1858, it was recognized as a single species: Eucalyptus microtheca. (The Eucalyptus genus has over 700 recognized species, and botanists have divided and subdivided this large pie into progressively smaller slices—to the point where most authors describe coolibah species in a hierarchy four to five layers deep under Eucalyptus.) Most authors agree that coolibah species are a sub-group of Australian box trees, and the two groups are closely related.[1]Hill, K. D. (1994). Symphyomyrtus section Adnataria series Oliganthae subseries Microthecosae. TELOPEA, 5(4), 743-771.

Currently, the Centre for Australian National Biodiversity Research (CANBR) and their internet-based EUCLID project is perhaps the most authoritative and up-to-date resource for eucalypts. The authors here currently recognize four discernible coolibah species, though mention is also given to other species in this specialized grouping, totaling ten species.[2]Brooker, M. I. H. (2000). A new classification of the genus Eucalyptus L’Her.(Myrtaceae). Australian systematic botany13(1), 79-148.

The four primary species listed by EUCLID:

  • Eucalyptus coolabah | inland coolibah On a practical level for woodworkers and turners, this is likely the most commonly seen commercial species. It is very dense and has a rich red heartwood (including burls) that most woodworkers associate with the name coolibah. All the mechanical data and written descriptions above are for this species.
  • Eucalyptus microtheca | northern coolibah Although this was the original species described, the name has now been narrowed to include a more particular definition of trees, primarily occurring in northern Australia. Unfortunately, older writings usually used the E. microtheca name in the broader sense and descriptions may actually refer to what is considered E. coolabah today. Nonetheless, trees from this narrower species definition produces heartwood that tends to be a darker grayish brown, sometimes with an olive cast. It also contains whitish mineral deposits in the pores that can be seen as “threads” even on the facegrain of the wood. These differences are believed to be caused by different climates and growing conditions of the trees.[3]Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 21–22.
  • Eucalyptus acroleuca | Lakefield coolibah This is a less-common species of coolibah, restricted to the Lakefield National Park area in Queensland, Australia. Since this is a protected area, it’s highly unlikely to see much of this wood commercially. However, this species yields wood that is very dark brown to nearly black, with an approximate average dried weight around 84.3 lbs/ft3 (1,350 kg/m3)![4]Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 26.
  • Eucalyptus victrix smooth-barked coolibah This is a more recently described species, being recognized in 1994 on the basis of its characteristic smooth, white bark throughout the tree.[5]Hill, K. D. (1994). Symphyomyrtus section Adnataria series Oliganthae subseries Microthecosae. TELOPEA, 5(4), 743-771. This species isn’t very common in woodworking applications, and the wood tends to be slightly lighter at around 65.5 lbs/ft3 (1,050 kg/m3).[6]Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 25.

There are also six remaining species also botanically classified in the same sub-grouping:
(Eucalyptus > Symphyomyrtus > Adnataria > Apicales > Aquilonares > Protrusae)

  • Eucalyptus argillacea | Mount House box
  • Eucalyptus chlorophylla | green-leaf box
  • Eucalyptus distans | Katherine box
  • Eucalyptus microneura | Gilbert River box
  • Eucalyptus obconica | obconica box
  • Eucalyptus tectifica | Darwin box

There are other closely-related box species that technically don’t fall into the same botanical sub-group but sometimes bear the name coolibah:

  • Eucalyptus orgadophila | mountain coolibah
  • Eucalyptus intertexta | inland red box Sometimes called bastard coolibah.

Images: Drag the slider up/down to toggle between raw and finished wood.

Do you have images of projects made from this wood species? You can submit them to me here.

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

Coolibah (endgrain 10x)
Coolibah (endgrain 1x)

Porosity: diffuse porous

Arrangement: exclusively solitary pores, sometimes occurring in diagonal/radial patterns

Vessels: medium to large, few to moderately numerous

Parenchyma: diffuse-in-aggregates, and weakly vasicentric

Rays: narrow to medium width; normal spacing

Lookalikes/Substitutes: Coolibah can be confused with other dense, reddish brown species of Eucalyptus, especially river red gum (E. camaldulensis), also occurring in eastern Australia. Jarrah is another species that can have a similar appearance, but is conversely found in western Australia, so mixups are less common.

Notes: Within the commonly seen species designated as coolibah, Eucalyptus coolabah tends to have reddish brown heartwood and lacks the contrasting mineral deposits in the pores, while the heartwood of E. microtheca tends to have more of a grayish olive cast, as well as white-colored mineral deposits in many of the pores, visible in the raw wood even on the facegrain. 

> Hardwoods > Myrtaceae > Eucalyptus > Related Species

The following is an alphabetical listing of all Eucalyptus species. For an more in-depth look at the various coolibah and closely-related box species, refer to the comments above.

Related Content:

References

References
1, 5 Hill, K. D. (1994). Symphyomyrtus section Adnataria series Oliganthae subseries Microthecosae. TELOPEA, 5(4), 743-771.
2 Brooker, M. I. H. (2000). A new classification of the genus Eucalyptus L’Her.(Myrtaceae). Australian systematic botany13(1), 79-148.
3 Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 21–22.
4 Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 26.
6 Dimitriadis, E. (2019). Distinguishing Coolibah Trees and their Woods. World of Wood, 72(2), 25.
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sven

A turned platter from Coolabah

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