Coincidence?

[Inziladun]

Originally Posted by Lalwendë

I noted in a thread not long ago that the Meneltarma on Numenor often makes me think of the Kaaba at Mecca, so this is an interesting thread!

Now, is it my imagination or is there something in one of the texts which states that the walls of Orthanc were constructed of Obsidian? That's not from meteorites but is an Igneous rock formed by volcanic activity (and very nice, too). And Tolkien noted that the walls around Minas Tirith were black and of the same stone.

If someone can clarify or not about this that would be excellent.

I don't recall anything saying it was made of Obsidian specifically. Of the Rings of Power and the Third Age in The Silmarillion simply says:

And in the circle of Angrenost, which Men call Isengard, (the Númenóreans) made the pinnacle of Orthanc of unbreakable stone.

The outmost wall of Minas Tirith was indeed said to be similar:

Its outward face was like to the Tower of Orthanc, hard and dark and smooth, unconquerable by steel or fire, unbreakable except by some convulsion that would rend the very earth on which it stood.

The Siege of Gondor ROTK

Appearance-wise it seems like enough to Obsidian, but I don't think that particular rock could be described as 'unbreakable'.