The Minerology Manual may be one of the most frustrating books I've ever purchased. I love so much of it, but it is also such a hot mess.
To begin with, the good:
This is the kind of world building supplement that I adore – one that provides what I like to call “fantastic naturalism”. It begins with elements which fill the role of fantasy entries of the periodic table. It then builds into minerals, rocks, soils, ores, metals, crystals and gemstones in a way that all fits with how actual geology might work in a magical setting. While reading the book I kept asking my wife, a geologist, about the accuracy of various things and most of it seemed fairly correct. The section on leylines is also fairly interesting and potentially useful. It would seem to play a large part of this fantasy geology but… we’ll get to that later.
The information on dwarven cities, clans and even full on dwarven conlang with script are great and full of inspiration. I loved the idea of the mesa dwarves and they cities are fairly well detailed. Additionally, the special locations are cool and very in line with what has come before. Finally, the adventures are pretty good and make for a nice little tour of many of the setting elements that have been included in the book.
But now my first gripe: Things are obviously missing or were incompletely changed.
I’m pretty sure there used to be a more complex or in-depth crafting system and a set of rules about mining. To begin with, the Hollowing the Earth section directly says it will provide rules for establishing and operating mines only to be followed up with ten fleshed out mines. Notably, these mines seem to refer to some set of rules that don’t exist like “Stages of Mine Life”. Additionally, in the appendix (whose name fits very appropriately since most of it seems to be vestigial) is a large chart for all of the listed items in the beginning of the book with DCs for Prospecting, Mining, Refining Type and Refining DC. Numbers which aren’t directly mentioned anywhere in the book.
There is also a series of charts in the appendix that list each of the “sample” ley lines as components of each of the elements, minerals and other materials. A blurb at the end of the chart indicates that it is there for crafting inspiration, but it feels like a lot more. This chart seems like part of a missing answer to the question “how does this all fit together?” Considering the leyline portion of the book is in the Crafting section for some reason, my guess is that there was supposed to be a much more in-depth crafting system that utilized the energy types from the leylines more explicitly. This book just contains SO MUCH that feels like it should all work together for something but in the end the crafting system just doesn’t utilize it at all. It is one of those instances of there being a noticeably shaped puzzle piece missing.
The second gripe is what rules there are in the book.
The crafting system is interesting in some ways. Using an expanding and retracting pools of d6’s to beat a DC that would normally face a d20 roll is a good way of doing things, I think, if non-standard for 5e D&D. The flaws and gains are interesting, too, and work well with the d6 system as listed. But the system is mussy and self-contradictory. Step 4 says to make a standard d20 based proficiency check adding your d6’s from before but the previous steps and the example afterwards only use the d6’s. Step 4 also mentions the GM calling for additional rolls to increase or decrease your d6 pool but gives no guidance on how many of these rolls should be made. My guess is that some of the DCs listed in the Appendix would have come into play here but got removed for some reason.
Then there is the Sapper class which has zero special abilities until 2nd level. (At least I assume – there isn’t a leveling chart of the class anywhere.) And their main power is to create explosives which they have recipes for but there is no information about what explosives or where these recipes come from. Later in the book is a list of equipment including explosives, mutagens and such that are listed as things the sapper can make but you have to guess that that is what these are for. Especially since the equipment section of the appendix say these are perfect for all who wish to “make a bang on their adventures”. The fact that there is no pricing or rarity listed for these items hints that they aren’t actually for sale and are actually class features for the class listed 30 pages back.
There are also 23 pages of tomes, sample books characters can find. Why they are in this book I’m not sure since they aren’t particularly dwarven or geological in any sense.
Finally, the book’s organization.
In some ways the organization of the books is useful for sussing out what was supposed to be here. For example, the Crafting the Earth chapter begins with leylines, is followed by the actual crafting rules and then followed by descriptions of ores, metals, crystals and gemstones. At face value this seems nonsensical but if you assume the leylines were supposed to play a much bigger part of the crafting rules it makes a lot more sense. Similarly, the chapter on mining begins with a list of fossils that don’t seem to relate to anything and then all the mines. I’m guessing maybe the fossils played a part in terms of the rules for running a mine. I’m not sure.
The organization just feels sort of arbitrary. The Children of the Earth chapter foes from description of the clans to the dwarven conlang to the adventures to a list of special locations to the new classes. The cities are listed under the mining section (which, I guess is called “Hollowing the Earth” but a number of the cities are above ground…)
And lastly the maps for the mines, cities and adventures are all crammed into one section of the appendix, two maps per page. It is inconvenient enough, but the maps are tiny for what is on them, especially the cities. I’ve got the page blown up to 110% and I still can’t read the text in the legends. The images don’t extract properly from the PDF, either, so there is no separating them out.
I’ve ragged on this book a lot but that’s mainly because I saw so much promise in it. The premise of creating a fantasy geology and a dwarven culture that goes around it is fantastic and the actual geology part is very well executed. I love the creativity involved. Maybe the book would have been better off being a system neutral reference instead of trying to cram half-baked 5e rules in there? I love what this book wants to be so much, but it just feels like it either got murdered in editing or trying to expand out into places it didn’t need to go.
Overall, I can’t recommend it for the price.