Sains Malaysiana 55(3)(2026): 561-571

http://doi.org/10.17576/jsm-2026-5503-16

 

Discriminating Walrus and Narwhal Tusks through Integrated Biomineralogical and Geochemical Analysis

(Membezakan Gading Walrus dan Narwhal melalui Gabungan Analisis Biomineralogi dan Geokimia)

 

LU XINGYU & AZIMAH HUSSIN*

Geology Program, Department of Earth Science and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Received: 29 August 2025/Accepted: 4 March 2026

Abstract

Marine ivory, derived primarily from walrus (Odobenus rosmarus) and narwhal (Monodon monoceros) tusks, is a culturally and economically significant but vulnerable resource. Effective regulation of its trade requires reliable and non-destructive methods for species identification, yet current approaches remain limited. This study systematically compares the mineralogical, microstructural, and geochemical characteristics of walrus and narwhal tusks using an integrated suite of analytical techniques, including SEM, XRD, Raman spectroscopy, EDX and XRF analysis. Results based on SEM, Raman spectroscopy, XRD, and XRF analyses show distinct diagnostic features: narwhal tusks exhibit tightly bound collagen fibers interwoven with elongated hydroxyapatite crystals and fine, uniform porosity, whereas walrus tusks display disordered crystal clusters, partial collagen degradation, and more pronounced porosity. Both tusks are dominated by carbonate-substituted hydroxyapatite, but XRD and Raman results indicate that walrus apatite crystals are larger, more crystalline, and show stronger fluoride substitution. XRF and EDX data further indicate species-specific elemental signatures, with elevated Na₂O, MgO, Al₂O₃, SiO₂, and SrO in walrus, and enriched Sb and Cd in narwhal. A novel discriminant criterion derived from quantitative XRF measurements based on the Al₂O₃/P₂O₅ ratio (threshold R₀ = 0.0033) reliably distinguishes the two species. These findings establish a robust, non-destructive framework for forensic identification of marine ivory, offering direct applications to wildlife law enforcement, trade monitoring, and cultural heritage conservation.

Keywords: Geochemical analysis; mineralogical characteristics; narwhal tusk; organic gemstone; walrus tusk

 

Abstrak

Gading marin yang diperoleh terutamanya daripada gading walrus (Odobenus rosmarus) dan narwhal (Monodon monoceros), merupakan sumber yang signifikan dari segi kebudayaan dan ekonomi tetapi dalam masa yang sama terdedah kepada ancaman. Pengawalseliaan perdagangan yang berkesan memerlukan kaedah yang boleh dipercayai serta tidak merosakkan untuk pengecaman spesies, namun pendekatan sedia ada masih terbatas. Kajian ini secara sistematik membandingkan cirian mineralogi, mikrostruktur dan geokimia gading walrus dan narwhal melalui penggunaan gabungan teknik analisis. Hasil kajian berdasarkan analisis SEM, spektroskopi Raman, XRD dan XRF mendedahkan ciri diagnostik yang jelas: gading narwhal memperlihatkan serat kolagen yang terikat rapat dan saling berjalin dengan kristal hidroksiapatit berbentuk memanjang serta keliangan yang halus dan seragam, manakala gading walrus menunjukkan kelompok kristal yang tidak teratur, degradasi separa kolagen dan keliangan yang lebih ketara. Kedua-dua jenis gading didominasi oleh hidroksiapatit yang digantikan dengan karbonat, namun hasil XRD dan Raman menunjukkan bahawa kristal apatite dalam gading walrus adalah lebih besar, lebih berhablur dan memperlihatkan penggantian fluorida yang lebih kuat. Data XRF dan EDX seterusnya menunjukkan pengenalan unsur khusus spesies dengan kepekatan Na₂O, MgO, Al₂O₃, SiO₂ dan SrO yang lebih tinggi dalam gading walrus, manakala gading narwhal diperkaya dengan unsur Sb dan Cd. Satu kriteria pembezaan baharu berasaskan pengukuran kuantitatif XRF menggunakan nisbah Al₂O₃/P₂O₅ (ambang R₀ = 0.0033) dapat membezakan kedua-dua spesies dengan berkesan. Keputusan ini mewujudkan satu rangka kerja pengenalpastian forensik gading marin yang mantap serta tidak merosakkan dengan aplikasi langsung dalam penguatkuasaan undang-undang hidupan liar, pemantauan perdagangan dan pemuliharaan warisan budaya.

Kata kunci: Analisis geokimia; cirian mineralogi; gading narwhal; gading walrus; permata organik

 

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*Corresponding author; email: haqqim@ukm.edu.my