Hello folks,

This blog post was written in response to a discussion with Mevans on the mod's Discord (where he got really jealous of my proximity to the Eastern Shore Granite ridge) where we were trying to establish: where would vanilla granite, andesite, and diorite spawn in Middle-earth? I took some inspiration from the Geologic map of Nova Scotia, and here are some of my findings.

The Rocks


Andesite is an igneous extrusive rock, which means it's typically associated with areas that are currently or used to be volcanic. They generally have small crystals, due to being formed from lava that solidified fairly quickly on the earth's surface. Andesite is common in the Andes; in fact, it's the main rock that makes up the entire mountain range.

Granite and Diorite

Both of these rocks are igneous intrusive rocks. That means they are typically formed when magma is introduced into a cavity fairly deep beneath the earth's surface. The extra insulation provided by all that earth causes the molten rock to solidify much more slowly, leading to bigger crystals. In reality, granite is much more common worldwide than diorite, but the two can form mixtures known as granodiorite, and a considerable amount of real-life granite is whitish (as in my locality), like Minecraft's diorite. Usually, when granite or diorite are visible at the earth's surface, it's because they were originally covered by a bunch of softer sedimentary rocks, which have since weathered away, leaving the harder igneous rocks exposed, often forming hills in the process.

Where would they be found?

According to lore, Middle-earth wasn't formed via billions of years of geologic processes (unlike the Earth), so I cannot say for sure what kind of rocks were present where. However, making this assumption isn't geologically very helpful, so, for the sake of this argument, I will be assuming that Middle-earth was formed the same way as the Earth: over billions of years.


Being a volcanic rock, an obvious location where andesite would be found is Far Harad Volcano, as well as Perdorogwaith. Although not explicitly stated in the lore, it is also highly likely that Erebor was also at one point a volcano, as well as many of the other isolated fixed mountains, and most of the islands in The Sea, including the Western Isles.

A mountain that deserves special attention is Weathertop. Based on its description (having a conical top, being 1,000 feet higher than the land around it), it was almost certainly a volcano at one time and should therefore contain lots of andesite. My theory -- and this could be wrong -- was that all the other Weather Hills are extinct volcanoes too; they're just older and have had more time to erode, and they too should be made of andesite.

Granite and Diorite

Being igneous intrusive rocks, these would almost certainly be found in two different areas:

  • deep underground in mountain biomes, i.e. the Misty Mountains, Grey Mountains, or
  • exposed in areas where softer rocks overlaying them have since eroded away.

The first category doesn't need much explanation, but the second deserves a bit more comment. The "mountain" Region Variants in Eriador, Lone-lands, Enedwaith, and Far Harad Jungle look like they were formed that way, as well as the Trollshaws (which, IMO, should be modelled after the Eastern Shore Granite Ridge as closely as possible), Emyn Muil, Ettenmoors, Coldfells, Pinnath Gelin, the hills of Dor-en-Ernil, and possibly Ithilien Hills, Dunland and the Uruk Highlands.

New rock type?

Currently, there are several types of rocks in the mod. Sandstone is often found beneath deserts, Gondor Rock is a good stand-in for limestone or marble (it's logical that uplifting could have formed the White Mountains that way), Sarnagarn could represent rhyolite (an igneous extrusive rock which is fairly common in mountains), Mordor Rock looks like basalt (igneous extrusive, common in volcanically active areas like Mordor), Salluirn I don't know, and regular stone could be either shale (sedimentary rocks), slate (metamorphosed shale) or quartzite (metamorphosed sandstone).

One type of rock that is fairly common worldwide and is notably missing from Middle-earth is gneiss. This is a metamorphic rock known for its banding, which is also commonly found in old mountains. Like granite, it would either be found in pockets deep underground (usually under mountains), or in areas where softer rocks have, over time, been eroded away. However, being a metamorphic rock, it would be found above either granite or diorite.

If anyone with a better knowledge of geology wants to improve on what I wrote above, please leave a comment.

Thanks for reading, everyone!

13:30, October 7, 2020 (UTC)

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