Rock Collecting

I have been wondering about this for a while, and have made a couple attempts--one of which nearly broke my back--at bringing home cool rocks for the fish tank, but I have not really found anything good so far. The stuff I collected turned out to be very iron-rich and it worries me to be putting stuff like that in any of my tanks.

I am thinking of doing an Iwagumi set-up sometime in the future, but I just don't want to pay big money for rocks. It seems silly to me. Being in a state with a lot of interesting geology and volcanism, we must have some places where there are interesting rocks like you see in those professional iwagumi set-ups, but I just don't know where to find them. I have been looking over lots of DNR resources including this very confusing but cool interactive map; [You must be registered and logged in to see this link.]

Anyone have good places for rock collecting that you are willing to share? Specifically volcanic-type rocks because they are supposed to affect water chemistry the least and are the coolest looking. I know we must have areas in WA with nice rocks, it's just a matter of finding them, I suppose

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not my rocks, just an example

I love the Seiryu stone (Aquarium co-op has it) and haven't found anything local that I like as much as it. It looks super in the tanks and grows great algae

im going to say that youll probably have to head over to the other side of the mountains for that kinda thing. we just get too much rain on the western side to have nice jagged rocks like that. most of what i manage to find is old river drainage. mostly conglomerates and sedimentary rocks. i never see too much igneous around which is what i assume your after. your best bet is to climb a mt. or something where rocks havent already been washed away. GL in your search, but its going to be a difficult one i think.

I collect all of my rocks at local rivers. I prefer smooth though. The volcanic, igneous type are to abrasive.

We don't have a lot of patches of porphyritic lava flows in our state that would produce the rock like above.  However, we do have a lot of columnar basalt, which I think makes an interesting geometric scene due to its hexagonal fracture pattern:

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There are roadcuts along both I-90 and Hwy 410 heading up toward the passes where chunks regularly fall off and are easy to collect.  If you want a specific location, National Forest Rd. 19 just over Chinook Pass is a good place to find it, and if you go down into the riverbed, you may find interesting quartz-based crystals.  This is very near a thunderegg dig site and there should be sky blue chalcedony in there at least.

I've also found roadcuts along NFR 70 to be fruitful (just east of Greenwater on 410), but be prepared to drive several miles up rough terrain.  Possibly the closest thing we have to those rocks you posted that I've seen was up over 4000 feet along NFR 7010/7012:

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For exactly what you want, head to McKenzie Pass in Oregon.  Perfect crumbly basaltic lava covers the ground.  There's an observatory there built entirely of that rock.

Mafic igneous rock like basalt is generally pretty safe.  What you will have to watch for with any porphyritic rock is deposition of minerals in the pockets, specifically salts, that can leach into your tank.

Hi All,

I like basalt, it can certainly add a different texture and shape to the hardscape. The challenge for me has been finding small enough pieces. These pieces are in a 75 gallon.

Basalt
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Thanks everyone for the suggestions, some good ideas here. That columnar basalt is indeed amazing, I remember seeing some up near Mount Baker along the Ptarmigan Ridge trail near Coleman Pinnacle. The problem with those is their size- most, if not all, is much too big for my little tanks, but great idea nonetheless. and here are some results I found from collecting a couple of places yesterday:

Mountain loop highway
Kelcema Lake / Deer Creek
- Not much here, some interesting rocks on the trail up to the lake but nothing that is lug-able back to the car. I did see some nice water lillies in the lake though, which was surprising considering it's a semi-alpine lake.

Sunrise Mine Trail
- Not much here either, good inspiration for vegetation but nothing as far as rocks go. There were some smoothed river rocks near the upper Stilliguamish crossing, but again most of the interesting stuff was too big to lug back on the trail. This is the location I got the iron-rich rocks from (only it was higher on the trail and I broke my back lugging them down) and the second time I didn't find much more

Ice Caves Trail
- Actually some interesting rocks that look like they either fell or were scoured off the face by glaciers. Some nice smoothed rocks and some more jagged ones. The main problem was that there were so many types of rocks; looking up to the face, there are at least 2 or 3 contact metamorphosis zones along that huge north face, so a few different types of rock have fallen down. I found a couple of fine-grained pieces that looked like tuff or shale of some kind which had quartz veins nicely arranged, but didn't end up bringing them back because they just weren't that impressive.