of venerating stones (including the Black Stone) arose not because such stones are "sacred for their own sake, but because of their relation to something holy and respected". The Indian Islamic scholar Muhammad Hamidullah summed up the meaning of the Black Stone: In recent years several literalist views of the Black Stone have emerged. A small minority accepts as literally true a hadith, usually taken as allegorical, which asserts that "the Stone will appear on the Day of Judgement (Qiyamah) with eyes to see and a tongue to speak, and give evidence in favour of all who kissed it in true devotion, but speak out against whoever indulged in gossip or profane conversations during his circumambulation of the Kaaba". Scientific origins The nature of the Black Stone has been much debated. It has been described variously as basalt stone, an agate, a piece of natural glass or—most popularly—a stony meteorite. , the curator of the Austro-Hungarian imperial collection of minerals, published the first comprehensive analysis of the Black Stone in 1857, in which he favoured a meteoritic origin for the stone. Robert Dietz and John McHone proposed in 1974 that the Black Stone was actually an agate, judging from its physical attributes and a report by an Arab geologist that the stone contained clearly discernible diffusion banding characteristic of agates. A significant clue to its nature is provided by an account of the stone's recovery in 951 CE, after it had been stolen 21 years earlier. According to a chronicler, the stone was identified by its ability to float in water. If this account is accurate, it would rule out the Black Stone being an agate, a basalt lava, or a stony meteorite, though it would be compatible with it being glass or pumice. Elsebeth Thomsen of the University of Copenhagen proposed a different hypothesis in 1980. She suggested that the Black Stone may be a glass fragment, or impactite, from the impact of a fragmented meteorite that fell 6,000 years ago at Wabar,<ref>{{cite journal|title=New Light on the Origin of the Holy Black Stone of the Ka'ba|last=Thomsen|first=E.|journal=Meteoritics|volume=15|number=1|page=87|bibcode = 1980Metic..15...87T|doi = 10.1111/j.1945-5100.1980.tb00176.x|year = 1980}}</ref> a site in the Rub' al Khali desert 1,100 km east of Mecca. A 2004 scientific analysis of the Wabar site suggests that the impact event happened much more recently than first thought and might have occurred within the last 200–300 years. The meteoritic hypothesis is viewed