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Miva mahogany

Scientific name

Dysoxylum mollisimum subsp. molle (formerly D. muelleri), D. cerebriforme. Family: Meliaceae

Other names

Miva; red bean; onionwood (these names apply to D. mollisimum subsp. molle, only)

Description

  • Rainforest tree grows 25–30m high.
  • Stem grows to 1m diameter.
  • Trunk can be heavily flanged at the base but is not prominently buttressed. Bark is brown with fine vertical fissures.
  • Bark is shed in small chips.
  • Freshly cut bark and sapwood have a strong onion-like odour.

Occurrence

  • Found in rainforests from the Clarence River, New South Wales, to the Daintree River, North Queensland.

Appearance

Colour

  • Heartwood is red-brown.
  • Sapwood is creamy pink and easily distinguished from heartwood.

Grain

  • Grain is medium to coarse, often interlocked.
  • Texture is uniform.
  • Soft tissue (parenchyma) gives a slight figure (pattern) to the tangential surface.

Uses

  • Construction: used, in the past, as sawn timber in general house framing, flooring, linings, mouldings and joinery but is rarely these days.
  • Decorative: furniture, plywood, shop and office fixtures, carving, turnery, joinery.
  • Others: used, in the past, for wine casks, brush stocks.

Properties

  • Density: 625-640kg/m3 at 12% moisture content; about 1.5m3 of seasoned sawn timber per tonne.
  • Strength groups: (S5) unseasoned, (SD6) seasoned.
  • Stress grades: F5, F7, F8, F11 (unseasoned); F7, F8, F11, F14 (seasoned) when visually stress graded according to AS 2082—2000, Timber—Hardwood—Visually stress-graded for structural purposes.
  • Joint groups: J3 unseasoned, JD3 seasoned.
  • Shrinkage to 12% MC: 4.3% (tangential), 2.7% (radial).
  • Unit shrinkage: 0.39% (tangential), 0.31% (radial)—these values apply to D. muelleri only.
  • Durability above-ground: Class 3 (life expectancy 7–15 years).
  • Durability in-ground: Class 3 (life expectancy 5–15 years).
  • Lyctine susceptibility: untreated sapwood is susceptible to lyctid borer attack.
  • Termite resistance: not resistant.
  • Preservation: sapwood readily impregnates with preservatives but the heartwood can’t adequately be treated using available commercial processes.
  • Seasoning: satisfactorily dries using conventional air and kiln seasoning.
  • Hardness: firm (rated 4 on a 6-class scale) to indent and work with hand tools.
  • Machining: machines, and turns well.
  • Fixing: no difficulty using standard fittings and fastenings.
  • Gluing: satisfactorily bonds using standard procedures.
  • Finishing: readily accepts paint, stain and polish.

Identification features

General characteristics

  • Sapwood: creamy pink, distinctly lighter than heartwood.
  • Heartwood: red-brown.
  • Texture: medium to coarse, grain often interlocked.

Wood structure

  • Vessels: medium to large, visible without a lens, mostly in short radial rows of 2–4 cells but with some solitary; lighter colour vessel contents are visible in many specimens; vessel lines prominent on longitudinal surfaces.
  • Parenchyma (soft tissue): abundant in fine, wavy, apotracheal bands of slightly lighter colour than the background.
  • Rays: fine, not visible without a lens.

Other features

  • Burning splinter test: match-size splinter burns to charcoal—can use to distinguish from the very similar, closely related, rose mahogany, which burns to a white ash.
  • Figure (pattern): pleasing but subdued figure, caused by the parenchyma bands; occurs on dressed tangential surfaces.

Research and resources

  • Boland, DJ, Brooker, MIH, Chippendale, GM, Hall, N, Hyland, BPM, Johnston, RD, Kleinig, DA and Turner, JD 2006, ‘Forest trees of Australia’, 5th ed., CSIRO Publishing, Collingwood, Australia.
  • Bootle, K 2005, Wood in Australia: Types, properties and uses, 2nd ed., McGraw-Hill, Sydney.
  • Ilic, J 1991, CSIRO atlas of hardwoods, Crawford House Press, Bathurst, Australia.
  • Queensland Government, DAF 2018, Construction timbers in Queensland: Properties and specifications for satisfactory performance of construction timbers in Queensland. Class 1 and Class 10 buildings, Books 1 & 2, Department of Agriculture and Fisheries, Brisbane.
  • Standards Australia, 2000, AS 2082—2000: Timber—Hardwood—Visually stress-graded for structural purposes, Standards Australia International, Strathfield, NSW.