Bluestone vs flagstone: you are comparing a stone to a category
Bluestone is a flagstone. Flagstone is not a rock type at all, it is a description of behaviour: any flat sedimentary stone that splits cleanly along its bedding into slabs you can lay. Bluestone is one particular stone that does that, a dense feldspathic sandstone quarried in northeastern Pennsylvania and the southern Catskills.
So the real question is not bluestone or flagstone. It is which flagstone, and the honest answer for most projects is the one quarried closest to you, because freight dominates the delivered cost of anything this heavy.
If you want the short version: bluestone is the hardest-wearing and most formal of the common American flagstones, it costs the most outside the Northeast because of haulage, and Arizona flagstone or Tennessee Crab Orchard will serve you as well for less if you live nearer to those quarries.
The flagstones on the American market
| Stone | Quarried in | Colors | Hardness | Material $/sq ft |
|---|---|---|---|---|
| Pennsylvania bluestone | NE Pennsylvania, southern Catskills NY | Blue-gray, or full-color lilac, rust, brown, green | Mohs 6–7 | $8–$22 |
| New York bluestone | Catskills, NY | Blue-gray | Mohs 6–7 | $8–$22 |
| Tennessee Crab Orchard | Cumberland Plateau, TN | Tan, gold, gray, pink | Mohs 6–7 | $9–$18 |
| Arizona flagstone | Coconino and Yavapai counties, AZ | Red, pink, buff, gold, cream | Mohs 6–7 | $7–$14 |
| Texas Lueders limestone | Shackelford and Throckmorton counties, TX | Cream, pearl, gold | Mohs 3–4 | $8–$14 |
That table contains the single most useful fact in this comparison. Texas Lueders is Mohs 3 to 4 and the others are 6 to 7, because Lueders is a limestone and the rest are sandstones. Calling all five “flagstone” hides a real difference in how they wear. If a supplier quotes you “flagstone” without naming the quarry, that is the question to ask.
What bluestone actually is
Bluestone is a feldspathic sandstone from the Catskill Delta, laid down in the Devonian roughly 370 million years ago. It is dense, fine-grained, and splits reliably along its bedding, which is why it became the paving and sidewalk stone of the northeastern United States.
Two products go by the name. Blue-gray bluestone, also called select, is the uniform blue-grey most people picture. Full-color bluestone carries lilac, rust, brown and green across the same slab, from iron and other minerals in the original sediment. They come out of the same quarries; the full-color material is more variable and often slightly cheaper.
Its reputation is earned. Bluestone handles freeze-thaw well, has good natural grip, and the sidewalks laid in Brooklyn and Philadelphia a century ago are still in service.
Cost, and why the number moves so much
From the found.rocks US cost guide, bluestone patio installed:
| Region | Material $/sq ft | Installed $/sq ft | 300 sq ft patio |
|---|---|---|---|
| Northeast (NY, NJ, PA, CT, MA, RI) | $8–$16 | $20–$40 | $6,000–$12,000 |
| Mid-Atlantic (MD, VA, DE, DC) | $9–$17 | $22–$42 | $6,600–$12,600 |
| Southeast (NC, SC, GA, TN) | $11–$19 | $25–$48 | $7,500–$14,400 |
| Midwest (OH, IN, IL, MI, WI) | $12–$20 | $26–$50 | $7,800–$15,000 |
| Mountain West (CO, UT, NM, AZ) | $14–$22 | $28–$55 | $8,400–$16,500 |
| West Coast (CA, OR, WA) | $16–$26 | $30–$65 | $9,000–$19,500 |
The same stone costs roughly 60 per cent more installed on the West Coast than in the Northeast. Nothing about the material changed. It was hauled three thousand miles.
That is the argument for buying regionally. A Denver homeowner paying Mountain West prices for Pennsylvania bluestone is buying freight; Lyons sandstone from Colorado does the same job with a fraction of the haul. In Phoenix, Arizona flagstone is the local answer at $7 to $14 per square foot in materials.
Where bluestone is worth the premium
Formal geometry. Bluestone is commonly sold thermaled and cut to dimension, which gives tight joints and a crisp grid. Irregular flagstone cannot do that.
Freeze-thaw. Dense, low-absorption stone in a climate with a hundred freeze cycles a year. This is what it was made for.
Matching existing work. If your street, steps or house already carry bluestone, nothing else matches it.
Wear. At Mohs 6 to 7 with a tight grain, it takes traffic that softer flagstones would not.
Where another flagstone is the better buy
You live far from the Catskills. Freight is the dominant cost, and your regional stone will usually beat bluestone on delivered price.
You want warmth in the color. Bluestone is cool-toned. Arizona flagstone’s reds and golds and Crab Orchard’s tans do something bluestone cannot.
You want irregular. Random-shaped flagstone laid with planted joints reads informally in a way dimensioned bluestone does not.
You are in a hot, dry climate. Freeze-thaw performance is not buying you anything in Phoenix, and pale flagstone runs cooler underfoot than blue-gray.
Two things to specify, whichever you choose
Thickness. Flagstone sold for patios is not adequate for driveways, and thin stock over a poor base cracks along its bedding. Set the thickness against the use before comparing prices, or you will be comparing different products.
The base. Most flagstone failures are base failures. Excavation, compacted sub-base, and the setting bed decide whether the patio is still flat in ten years. Two quotes that differ by thousands usually differ underneath the stone, where you will never see it.
Then get three quotes
Compare the base build-up, the setting method, the joint treatment and the falls, not just the rate per square foot. Our US stone cost page carries installed ranges for every material and application we cover, so you can check a quote against the market before you sign it.
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