Evidence of the anthropogenic origin of the ‘Carmel sapphire’ with enigmatic super-reduced minerals

Abstract

Corundum with inclusions of enigmatic super-reduced (SR) minerals was found in mineral separates received as a result of alluvial sediment exploration near Mt Carmel, Israel by the Shefa Yamim Company. This corundum, registered as "Carmel sapphire TM " (CS), has been an object of numerous publications by W. Griffin's scientific team, in which they propose a questionable hypothesis of CS formation at the crust-mantle boundary with the participation of CH4+H2 fluids. Often the CS is in small fragments of breccia with white cement, which in the opinion of Griffin et al. is a carbonate-cemented volcanic ash. Our investigation of the "white breccia" showed that it consists of unsorted angular fragments of CS from 1 m to 7 mm in size cemented by aluminium hydroxides (bauxite) and is a waste product of the fused alumina process, i.e. it has an anthropogenic origin. Phases typical for slags of fused alumina production and metallurgical slags were identified in the "white breccia". CS has numerous microscopic spherical inclusions of Si-Fe alloy indicating that the removal of Si and Fe from the corundum melt occurred at a temperature above 2000С. Osbornite, TiN, from CS has a chemical zonation characteristic of osbornite from fused alumina with enrichment of central zones in carbon.Comparison of the growth heterogeneity of CS and "electrocorundum" indicates that the crystallization of the corundum melt proceeded in a similar way. Unfortunately, in the case of CS from Carmel locality,

Reply to the discussion of Galuskin and Galuskina (2023) “Evidence of the anthropogenic origin of the ‘Carmel sapphire’ with enigmatic super-reduced minerals” by Griffin et al. (2023)

“…Indeed, there are cases where skeletal osbornite crystals can be found completely inside corundum. In our samples, osbornite is typically confined to glass inclusions (Galuskin and Galuskina, 2023, figs S5D, S6C, supplementary materials).…”

“…The investigation of this specific 'white breccia' showed that it is a furnace charge (calcined bauxite) for electrocorundum production mixed with waste from its production. That led us to write a critical paper on the genesis of Carmel sapphire (Galuskin and Galuskina, 2023).…”

“…A powder-diffraction pattern was not produced because of a limited amount of böhmite-like material and its partial amorphisation. In figures 8d and 8f (Galuskin and Galuskina, 2023) one can see the differences between the EDS spectra for corundum (Al 2 O 3 with trace of Ti) and the böhmite-like phase (∼AlOOH). We agree that the identification of this phase is incomplete, however the data obtained undoubtedly indicate the presence of aluminium hydroxide, which we think was a main component of the charge in electrocorundum production.…”

“…At this point, we can close the discussion with two brief conclusions: (1) Griffin et al (2023) debate plenty of secondary issues that divert attention from the main object, 'white breccia', which is key to solving the problem of Carmel sapphire genesis; (2) 'white breccia' (in the form of individual samples) exists and consists of the waste of electrocorundum production. However we decided that readers can draw their own conclusions after reading our paper (Galuskin and Galuskina, 2023) and the discussion connected with it; we answer most of the remarks of Griffin et al (2023) below.…”

“…In our paper (Galuskin and Galuskina, 2023) we provide mineralogical evidence that 'Carmel sapphire' has an anthropogenic genesis based on the study of 'white breccia', which consists of the waste of electrocorundum (fused alumina, refractory abrasive material) production. It seems if there is no 'white breccia', then our evidence of the anthropogenic genesis of Carmel sapphire does not matter.…”