So pgs. 183-184 of the Bible states that mages can't astrally project through earth. I'm assuming this means "earth" as in "The Earth", rather than simply earth. Because if that were the case, every secure building in the world would have perimeter walls lined with dirt. However, the book does state that many secure facilities are built underground to minimize astral intruders.

My quick and, uh, dirty (SORRY) solution to this was to state that a certain amount of dirt/earth is unpassable. Say, half a kilometer or more. But this may be missing something important.

Thoughts?

I think you are correct in principle. For comparison in SR3 there were eventually specific rules for how much dirt mattered. I think around a meter an hour, which effectively meant 6 or more meters of dirt was an effective barrier. Too much to use everywhere as a security precaution, but small enough that it could be used as one if you really wanted to.

Anyone remember a piece of fiction from one of the books (Awakenings or SR2 Grimoire IIRC) where the basement of a building could not be pentrated because it was made from unworked river stones? Do natural building materials retain their "natural" astral object properties?

I would say 'yes', because it's cool.

What if you have masking? That lets you seep through wards.

I assume you're thinking about how (at least in SR3) someone with masking could potentially slip through a ward, fooling it into thinking the intruder was allowed to pass through.
My opinion is that this has nothing to do with that.
Spoofing a ward with masking is more like fooling security into letting you walk through a guarded hallway. Passing through the earth is more like just trying to walk through the wall.
It's nice that you can sort of do it, but it's easy to get trapped and die if you go past the point of no return.

the way it has worked in previous editions is that the earth in question must be a) physically connected to the planet, and b) unworked. if you shovel bunch of dirt into a pile around your building, yes, it will be impassible*. if you work it in any way--adobe bricks, for instance--it will be passible. and, yes, many secure facilities are built underground in order to make them more secure.

*astral forms actually can pass through the earth, but it takes a longass time: 30 minutes per meter, base, divided by successes on a Cha (4) test, in SR3.

Also, T:AL (as well as a couple of the novels) mentions a metamagic that allows an initiate to travel through solid rock. Since this was one of those 'lost in the depths of time' techniques and only GDs and immortal elves know it, I guess we can ignore it.

What if it's a spirit of earth?

Then it isn't "The Earth" it's a living creature. There are seperate rules for projecting through creatures.

Maybe you could have its astral form engulf your astral form and take you with it; or is that only a mundane ability?

i think he may have been asking about whether or not a spirit of earth could project through the planet. i would say it cannot, since it's not noted as being able to do so. judging from previous editions, though, the spirit could use its Movement power on itself or on astral forms the mage designates.

If that's the question I'd handle it the same way as you.

I think the key to Earth being impermeable is that the Earth had to still be natural. A living, unprocessed, non-sterile mixture of stuff that could or does support life. I don't think you could drop sandbags on a building, and called it projection proof. Course, you still have to ward any doors, windows, overly-large ventilation shafts (ha-ha!), etc...

Though, come to think of it, depending on the area going underground isn't necessarily an option either. How far down would you have to go under New York to reach natural earth nowadays?

Pretty far, but if you warded the entryway, and made the access tunnel wind and bend enough, the projecting mage may not be able to find his way down in time... After all, you can't see where you're going if you're surrounded by Gaia.

My interpretation is that it meant "THE Earth", as in spiritually. Some dirt hastily piled up, or rocks as part of a building wouldn't count; even a flourishing garden, if it is sufficiently separated (in a high rise building, or separated from the earth completely by artificial materials) wouldn't.

But any natural earth formation, or possibly even *ancient* earthen constructs (old earthen fortresses, ancient pyramids that could be confused with hills, etc) that have had enough time to be reclaimed (so to speak) by the Earth would count.

Of course, this isn't directly said in the book, it's just my interpretation.

As far as it being impossible to astrally project through the Earth goes... yeah, it only slows you down, but when you combine that with the fact that you lose essense as you project (1 per hour, iirc), you realize that doing so is very risky business

So it's really an 'either/or' scenario. Someone who learned the metamagic for [physically] moving through rock could go through the natural earth, but not through quarried stone or concrete. Someone who was projecting could get through the concrete, but not through the natural earth. Lining your basement with concrete walls should pretty much cover both scenarios.

A corporation has a dome-shaped building and covered the entire building with earth. They planted grass on the earth and added a sprinkler system to make sure it remains living earth. Well this runs into the same issue that ivy-covered buildings run into. A runner mage can be a hundred meters away and cast a mana or sterlize type spell that "kills" a section of the earth on the building. Then they can just astrally walk right in. The only effective means ( cost-effective anyway ) is to cover the living earth on the dome-shaped building with a layer on non-living material. A mage can't target something he can't see and as non-living materials are still visible on the astral it'll keep it spell proof unless one of the runners comrades sneaks up to the building and cuts a hole in the non-living layer. ( But that's what security camera's are for ) This increases maintainence costs for the living earth as grass and fresh air or no longer an option. The non-living layer should have a high object resistance as well ( industrial plastic and the like ) The last thing the corp wants is the mage casting some sort of "transparency" spell on the non-living barrier and then targetting the living earth.

At this time the corp has got to be wondering why they didn't just go with using walls filled with high density living bacteria gas. It's got about the same protective benefit and provides a few additional benefits.
1) Since the "living earth" to be really effective can't be exposed to outside air, its upkeep can't be any cheaper than the high density bacteria gas.
2) Any breach in the walls could be detected by pressure sensors in the wall that monitor the gas pressure.
3) As long as the bacteria gas is constantly in motion ( which it pretty much needs to be anyway to keep the gas "alive") then any "hole" caused by a mana or sterilization spell would quickly close as new gas replaces the old gas.
4) If some inventive runners kill a large portion of the gas say by injecting the wall with some sort of sterilizing agent, the bacteria gas is a lot easier to replace then "dead earth".

Red is correct

Look at biofibre and other barriers.

You cannot astrally pass through living organisms.

Earth - Dirt - contains billions of microscopic living organsisms per cubic foot.

if you had a building covered in a layer of dirt only 6" thick that has a sustained ecology of living organsims you could not pass through this.

now the same principles apply as the biofibre.. kill it and you can pass.

spray the dirt with a cocktail of herbicide and insecticide and you kill off all living organsims, or you apply high heat and kill everything

of course as a gm i would have the feeding system for this ecology kick in after the party in question passes through. the water traveling through the dirt will carry new organisms into previously destroyed area.

now the question of rock
i think this should fall into two catagories
surface rock & deep rock/earth

surface rock will have fissures, cracks and stratifcations that will allow micro organism to penetrate thus creating another living wall.

deep rock and earth
we know that mana flow in the lei lines and that the earth holds a great amount of mana. earth as a conductor of mana much like wires conduct electricity. so even at great depths you cannot pass through earth because of the vast mana sea that resides inside the earth.

load cannons & fire away chummers

Sure... but considering that even Lofwyr is not listed as having this ability...

I think there may be a way to reconcile the divide between two different ideas here. One idea is that Earth may not be permeable due to organisms therein, and the other being Earth has an aura due to being an astral entity (of some undefined sort). The two ideas are not necessarily independent.

For example, we know that you can astrally project through ordinary, mundane, non-perceiving people that are not dual natured. They throw an aura on to the astral, but they are not astrally present. Thus the idea that Earth blocks astral projection due to the content of life doesn't seem so valid. Kudos for the counter-point!

So, why did that idea take hold in the first place? After thinking about it, I came to the conclusion that the reason I adopted the idea had less to do with the presence of life, and more to do with, "How do I dissociate between dirt that is Earth, and ... dirt?" And I found that for some reason I identified the ability to support life as a condition for dirt being a part of Earth, and thus possessing an astral presense.

Maybe we should consider building a list of prerequisites for determining whether dirt a part of the Earthen something that projects a planet sized astral presense.

1. Ability to support life?
2. Low concentration of highly processed materials?
3. Physical proximity? I.E. must it be rooted to other dirt that qualifies as Earth, such that you could draw a line from dirt to more dirt to more dirt that eventually goes down to the molten core?

Experiment on point 3. If filled in a strip mine with highly processed plasteel, and then filled the giant "cup" with living earth, would that space be astrally dead? Or would it be absorbed by the identity of Earth?