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Rough stones for tumbling decide the result more than any machine or grit. A month of careful tumbling can't fix rock that's porous, cracked or too soft. Bad rough is also the hidden reason many first batches come out dull, because one crumbly stone sheds grit that scratches everything else in the barrel.
So the questions to ask about any bag are simple. What is it? (one material or a mix). How hard is it? (Mohs 7 is the sweet spot). What size are the pieces? (it has to fit your barrel). How much is in it? (enough to fill your barrel properly). We compared seven bags on those four points, using only what each seller publishes on its listing.
Quick Picks
- Best Overall: National Geographic Rock Tumbler Refill Kit with 5 Lbs. Rough Rocks. Best for four labeled mixes plus grit for five cycles.
- Best Hard-Stone Mix: Mooseman Minerals 3 lbs Agate, Jasper, Petrified Wood Mix. Best for a beginner-proof, hardness-matched bag.
- Best Single-Material Agate: Hypnotic Gems Materials 3 lbs Natural Agate. Best for an all-agate batch with no sorting.
- Best for Small Barrels: Mooseman Minerals 3 lbs Small Rainbow Petrified Wood. Best for 1 to 3 lb barrels, with US-sourced wood.
- Best Jasper Sampler: National Geographic 1 Lb. Jasper Refill. Best for kit owners who want eight jaspers and grit in one bag.
- Best Variety Bag: FORBY 3 lbs Madagascar Stones Mix. Best for experienced tumblers happy to sort by hardness.
- Best Crystal Mix: National Geographic 3 Lbs. Rough Gems. Best for amethyst and quartz fans who'll use cushioning media.
Rough Stones Comparison Table
| Bag | Best for | Weight | What's in it | Stated size | Extras |
|---|---|---|---|---|---|
| NatGeo 5 Lbs. Rough Rocks | Overall | 5 lb | 2 lb gemstone mix, 1 lb agate, 1 lb Madagascar, 1 lb jasper | Not stated | 20 grit packets, 5 jewelry settings, guide |
| Mooseman Agate/Jasper/PW Mix | Hard-stone mix | 3 lb | Agate, jasper, petrified wood | 1 to 2 in | None |
| Hypnotic Gems Agate | Single material | 3 lb (1/2 to 18 lb offered) | Agate from Asia | 1 to 1-1/2 in average | None |
| Mooseman Small Petrified Wood | Small barrels | 3 lb | Arizona rainbow petrified wood | About 1/2 to 1 in | None |
| NatGeo 1 Lb. Jasper | Jasper sampler | 1 lb | 8 jaspers incl. mookaite and kabamba | Not stated | 4 grits, jewelry fastenings, guide |
| FORBY Madagascar Mix | Variety | 3 lb | Mixed Madagascar stones | 1 to 2 in, 1.25 in average | None |
| NatGeo 3 Lbs. Rough Gems | Crystal mix | 3 lb | Gemstone mix incl. amethyst and quartz | Not stated | 4-stage grit, jewelry accessories |
The Best Rough Stones for Tumbling, Reviewed
National Geographic Rock Tumbler Refill Kit with 5 Lbs. Rough Rocks: Best Overall
Who it's for: kit tumbler owners and beginners who want a lot of rough, already sorted by type, and grit to go with it.
This is the most complete refill we found. National Geographic splits the 5 lb into four separate mixes: 2 lb of gemstone mix, 1 lb of agate, 1 lb of Madagascar mix and 1 lb of jasper. That separation is the real value. You can run the agate and jasper together (both about Mohs 7), and keep the more varied gemstone and Madagascar mixes for later batches once you've sorted them.
The box also has 20 grit packets, which National Geographic says is enough for five complete tumbling cycles in any tumbler. You also get five jewelry settings, a storage pouch and a learning guide. The brand rates it for ages 8 and up.
The catch is that the listing doesn't give piece sizes, and the gemstone and Madagascar mixes will contain stones of different hardness. Sort them before they go in the barrel. Our guide to the best rocks for tumbling shows how.
Pros
- 5 lb of rough in four labeled mixes
- Grit for five full cycles included
- Agate and jasper bags can run together
- Works in any brand of tumbler
Cons
- Piece sizes not published
- Mixed bags need sorting by hardness
- Packet grit isn't labeled by mesh size
National Geographic Rock Tumbler Refill Kit with 5 Lbs. Rough Rocks
by National Geographic
Mooseman Minerals 3 lbs Bulk Rough Agate, Jasper, Petrified Wood Stone Mix: Best Hard-Stone Mix
Who it's for: beginners who want to load a barrel straight from the bag with no sorting.
This bag contains the three stones every tumbling guide recommends first: agate, jasper and petrified wood. Rocktumbler.com lists all three at Mohs 7, so they wear at the same rate and finish together. That makes this the most forgiving mixed bag here.
Mooseman Minerals lists the pieces at 1 to 2 inches in mixed sizes and the stones as untreated. Note the size: Lortone rates its 3A barrel for stones up to 1-1/4 inches, and Rocktumbler.com suggests 1/4 to 1-1/2 inches for 3 lb barrels. In a small barrel, set the biggest pieces aside or save them for a larger machine. In a 6 lb or 12 lb barrel, this size range is ideal.
Pros
- All three stones are hardness-matched at about Mohs 7
- Classic, forgiving beginner materials
- Mixed sizes improve grinding action
- Untreated stones, per the listing
Cons
- Largest pieces are too big for 3 lb barrels
- No grit or extras
- Colors vary by batch
Mooseman Minerals 3 lbs Bulk Rough Agate, Jasper, Petrified Wood Stone Mix
by Mooseman Minerals
Hypnotic Gems Materials 3 lbs Natural Agate Stones from Asia: Best Single-Material Agate
Who it's for: anyone who wants a whole barrel of one material and the simplest possible timeline.
A single-material bag removes all the guesswork. Every stone wears at the same rate, so stage times from the manuals apply directly. Hypnotic Gems lists an average size of 1 to 1-1/2 inches, which suits most 3 lb barrels if you add some small pieces or ceramic media. It sells the same agate in quantities from 1/2 lb up to 18 lb, so you can match the bag to your barrel.
The listing is honest about one thing worth knowing: the photos show stones soaked in water to show their potential. Dry rough looks much duller. It also tells you each stone is unique and will be similar to, not identical to, the pictures.
Agate rewards patience in the coarse stage. Plan on at least a week, and often two, before moving on. Our upcoming agate tumbling guide covers it in detail.
Pros
- One material, so one predictable timeline
- 1 to 1-1/2 in average suits common barrels
- Sizes from 1/2 lb to 18 lb
- Listing is clear that photos are wet
Cons
- Agate can hide hollow or crystal-lined centers
- No extras
- Fewer sellers stock it at times
Hypnotic Gems Materials 3 lbs Natural Agate Stones from Asia
by Hypnotic Gems
Mooseman Minerals 3 lbs Small Bulk Rough Rainbow Petrified Wood from Arizona: Best for Small Barrels
Who it's for: owners of 1 to 3 lb kit and hobby barrels who keep running into rough that's too big.
Most bulk bags run 1 to 2 inches, which is awkward in small barrels. This one is the exception. Mooseman Minerals lists the pieces at about 1/2 to 1 inch long, and the material is Arizona "rainbow" petrified wood in reds, blacks, whites, browns and grays.
Petrified wood is largely the same material as jasper, according to Rocktumbler.com, and it's one of its top three beginner stones. Small pieces also mean more stones per batch, which is satisfying in a 2 lb barrel.
Two cautions. Small rough loses a larger share of its size in coarse grit, so don't over-run the first stage. And petrified wood can crack along its grain; cull any piece with a visible split.
Pros
- Small pieces fit 1 to 3 lb barrels
- Hard, jasper-like material
- US-sourced, per the listing
- Many stones per batch
Cons
- Small stones shrink noticeably in coarse grit
- Too small to fill a large barrel well alone
- Watch for grain-line cracks
Mooseman Minerals 3 lbs Small Bulk Rough Rainbow Petrified Wood from Arizona
by Mooseman Minerals
National Geographic Rock Tumbler Refill Kit 1 Lb. Jasper Rocks: Best Jasper Sampler
Who it's for: owners of 1 to 2 lb kit tumblers who want a new batch with grit included.
National Geographic packs eight jaspers into this 1 lb bag: mookaite, kabamba, zebra, picture, red, Dalmatian, polychrome and yellow jasper. Four grades of grit (coarse, medium, fine and polish), jewelry fastenings and a learning guide come with it.
It's the right size for small kit barrels. One detail worth knowing: Rocktumbler.com notes that Dalmatian stone isn't actually a jasper, and lists it at Mohs 5.5 to 6.5, softer than true jasper at 7. Watch the Dalmatian pieces in coarse and pull them early if they're shrinking faster than the rest.
Pros
- Eight varieties for a colorful batch
- Grit and jewelry findings included
- Right size for 1 to 2 lb barrels
- Jasper is the most durable beginner stone
Cons
- Only 1 lb
- Dalmatian stone is softer than true jasper
- Piece sizes not published
National Geographic Rock Tumbler Refill Kit 1 Lb. Jasper Rocks
by National Geographic
FORBY 3 lbs Bulk Rough Madagascar Stones Mix: Best Variety Bag
Who it's for: experienced tumblers who enjoy sorting and want the widest range of colors.
Madagascar mixes are popular because they contain so many materials. FORBY lists 1 to 2 inch pieces, averaging 1.25 inches, in a 3 lb bag, and says the photos were taken wet to show color and clarity.
That variety is also the risk. A Madagascar mix can contain stones from soft to quartz-hard, and the listing doesn't name what's inside. Before tumbling, sort the bag into hardness groups with a simple scratch test, and run each group separately. Rocktumbler.com's hardness rule applies: mixing a Mohs 7 stone with a Mohs 5 stone means the soft one is ground away before the hard one is shaped.
Pros
- Wide variety of colors and materials
- 1.25 in average size suits mid-size barrels
- Honest wet-photo disclosure
Cons
- Contents not itemized
- Needs sorting by hardness
- Not a beginner bag
FORBY 3 lbs Bulk Rough Madagascar Stones Mix
by FORBY
National Geographic Rock Tumbler Refill Kit with 3 Lbs. Rough Gems: Best Crystal Mix
Who it's for: tumblers who want amethyst and quartz in their finished batch and are willing to cushion them.
This 3 lb gemstone mix highlights amethyst and quartz, and includes 4-stage grit and jewelry accessories. Three pounds is enough to fill a 3 lb barrel properly, which most kits can't do on their own.
Crystalline quartz is beautiful polished but bruises easily. Rocktumbler.com lists obsidian, glass and crystalline quartz as materials that bruise, and recommends cushioning them, for example with a large share of small ceramic media. Plan on adding media and checking the coarse stage often. Our guide to ceramic media for rock tumbling explains how much to use.
Pros
- 3 lb fills a 3 lb barrel
- Amethyst and quartz polish to a bright, glassy finish
- Grit and jewelry accessories included
Cons
- Crystal quartz bruises without cushioning
- Mix contents and sizes not fully itemized
- Less forgiving than agate or jasper
National Geographic Rock Tumbler Refill Kit with 3 Lbs. Rough Gems
by National Geographic
Buying Guide: How to Choose Rough Stones for Tumbling
Hardness First
Pick stones near Mohs 7 for your first batches. Rocktumbler.com puts the ideal range at about 6 to 8, and says stones harder than 8 cut slowly and often polish poorly. The manuals assume this hardness too. Lortone's instructions call for 5 to 7 days per stage, and Harbor Freight's for 7 to 10 days of coarse grit, and both are written for stones like agate and jasper.
For softer rough, shorten the coarse stage. Rocktumbler.com's rule of thumb is about 1-1/2 fewer days for each Mohs point below 7. Our rock tumbling timeline calculator does the math.
Single Material vs Mixed Bags
| Bag type | Pros | Cons | Best for |
|---|---|---|---|
| Single material | One predictable timeline; no sorting | Less color variety | Beginners, big barrels |
| Hardness-matched mix | Variety and a shared timeline | Fewer options on the market | Beginners who want color |
| Unsorted mix | Most variety per pound | Must be sorted by hardness | Experienced tumblers |
Size Must Fit Your Barrel
Rocktumbler.com recommends a mix of about 1/4 to 1-1/2 inches for 3 lb barrels such as Thumler's A-R1 and A-R2, and 1-1/2 to 3 inches for large barrels like the Thumler's A-R12 and Model B. Lortone rates its 3A for stones up to 1-1/4 inches. A good rule: nothing bigger than about half the barrel's diameter.
A range of sizes helps. Lortone recommends assorted sizes because small stones fill the gaps between large ones. If your bag is all one size, add ceramic media.
Buy Enough to Fill the Barrel
Lortone tells you to fill the barrel half to two-thirds full. Thumler's says its 3 lb barrel tumbles about 2 lb of rock. In practice:
- 2 lb kit barrel: about 1 to 1-1/2 lb of rough
- 3 lb barrel: about 2 lb
- 6 lb barrel: about 4 lb
- 12 lb barrel: about 6 to 8 lb
Expect losses. Rocktumbler.com says coarse grit removes roughly 10% to 30% of the rock's volume, and some stones will crack and need culling. Buy a little more than you need, and keep ceramic media on hand to top up. Our rock tumbler grit guide covers grit amounts for each barrel size.
Read the Listing for Red Flags
- "Assorted" with no list of contents. Expect mixed hardness.
- No size range. Pieces may be too big or too small for your barrel.
- Dyed or "stabilized" material. Dye wears off in the tumbler.
- Gem names at bargain prices. Rocktumbler.com says rough sold as ruby or sapphire has been consistently unpolishable in its experience.
- Wet photos. Normal and fine, but dry rough will look duller until polished.
Inspect Before You Tumble
Wash new rough and look closely. Rocktumbler.com's four checks apply to bought rock just as much as found rock: it should be hard, dense, free of fractures and smooth to the touch. Rub two pieces together firmly; anything that sheds grains stays out. Break cracked pieces along the crack. Then follow our step-by-step rock tumbling guide.
How We Chose
We didn't buy and tumble these bags ourselves. We researched them. We compared what each seller publishes (materials, weight, piece size and extras) against the hardness and size guidance in Rocktumbler.com's tumbling guides and the fill and timing instructions in Lortone's and Harbor Freight's manuals. We favored bags that name their materials and sizes, and we left out listings that had no active offers when we checked. Rough is a natural product, so contents vary from batch to batch.
FAQ
What is the best rough rock for a rock tumbler?
Agate, jasper and petrified wood. They're around Mohs 7, dense and durable, and they tolerate the one-week-per-stage schedules in Lortone, Harbor Freight and Kingsley North manuals. A bag of one of these, or a mix of the three, is the safest first purchase.
How much rough do I need for my tumbler?
Fill the barrel about half to two-thirds full, per Lortone. Thumler's says its 3 lb barrel tumbles about 2 lb of rock, so a 3 lb bag fills a 3 lb barrel with some to spare for culls. A 6 lb barrel needs roughly 4 lb, and a 12 lb barrel 6 to 8 lb.
Can I tumble a mixed bag of rough all at once?
Only if everything in it shares a similar Mohs hardness. Many mixed bags, especially Madagascar and Brazil mixes, contain soft stones alongside quartz-family rock. Sort them into hardness groups first, or the soft stones will be ground away before the hard ones are shaped.
Why does rough look so much brighter in product photos?
Sellers usually photograph rough wet, which shows roughly how it will look polished. Several listings, including Hypnotic Gems and Mooseman Minerals, say so on the page. Dry rough looks dull and chalky until it has been through the full tumbling process.
Is it cheaper to collect my own rough?
Usually, if you have access to good collecting ground where it's allowed. Beach and stream agate, jasper and chert are excellent. Rocktumbler.com warns that rounded beach stones still need a full coarse stage to remove their weathered rind and impact bruises, and that a large share of collected stones should be culled.
Verdict
For most people, the National Geographic 5 Lbs. refill is the best rough stone buy: four labeled mixes and grit for five cycles. If you want a bag you can pour straight into the barrel, the Mooseman Minerals agate, jasper and petrified wood mix is the most forgiving. Owners of small barrels should start with Mooseman's small Arizona petrified wood.