Stone Hardness Ranking - From Soapstone (Talc) to Granite
At japanstones.shop we present the work of twelve Japanese stone masons and sculptors exclusively to international buyers. From time to time, people bring us interesting items asking if we can sell them overseas. Today’s article introduces a phoenix stone carving, most likely made in China in the 1970s–1980s. Because it is not by a Japanese artisan, we will not list it for sale here, but the stone itself has features worth sharing.
What Is the Phoenix Carving Made Of?
The phoenix is carved from talc (soapstone). On the Mohs scale it is hardness 1—one of the softest minerals on earth. It scratches easily (even with a fingernail) and feels silky, which is why it’s called “soapstone.” Its softness enables delicate piercings and flowing lines, but it is not suited to long-term outdoor use where abrasion and weathering occur.
Mohs Scale: Origin and What It Measures
The Mohs hardness scale was introduced in 1812 by German mineralogist Friedrich Mohs (1773–1839). It ranks minerals by their scratch resistance from 1 to 10, determined by whether one mineral can scratch another. Importantly, Mohs hardness indicates surface scratch hardness only; it is not a direct measure of bulk strength such as compressive strength or toughness. For example, quartz (Mohs 7) can scratch glass but is brittle under impact.
Today the Mohs scale remains widely used across jewelry, mineralogy, and the stone industry; in stone descriptions it is common to write “Mohs hardness X.”
Mohs Hardness Ranking (Definitive Table)
| Mohs | Representative Mineral / Stone | Other Minerals / Stones (same band) | Everyday Reference | Common Uses |
|---|---|---|---|---|
| 1 (softest) | Talc (Soapstone) | Graphite, Kaolinite (Kaolin) | — | Talc powder; soapstone carving; pencil lead; ceramic filler |
| 2 | Gypsum | — | — | Plaster casts; drywall |
| 2.5 (ref.) | — | — | Human fingernail (~2.5) | Field scratch test reference |
| 3 | Calcite | Marble, Limestone, Travertine | Copper coin (~3–3.5) | Marble sculpture; architectural trim; cement/lime source |
| 4 | Fluorite | — | — | Decorative stone; glass/flux |
| 5 | Apatite | — | Steel nail or knife (~5) | Apatite gems; phosphate fertilizers |
| 5.5 (ref.) | — | — | Window glass (~5.5) | Common comparative reference |
| 6 | Orthoclase Feldspar | Basalt (~6) | Porcelain tile (~6) | Ceramics; glass raw materials; building stone |
| 6–7 | Granite (Feldspar ~6 + Quartz ~7) | — | Hardened steel file (~6.5) | Stone lanterns, Buddha statues, monuments, exterior architecture |
| 7 | Quartz | Quartzite (~7) | — (scratches glass) | Crystal; glass; optical components |
| 8 | Topaz | — | — | Gemstone |
| 9 | Corundum | — | Alumina sandpaper | Sapphire & ruby gems; abrasives |
| 10 (hardest) | Diamond | — | Diamond file/cutter | Jewelry; industrial cutting & polishing |
Notes: Everyday-item values are practical approximations. Mohs is a relative surface hardness scale; steps are not equally spaced (the gap from 9 to 10 is especially large).
Soapstone vs. Granite — “Soft Art” and “Lasting Form”
- Soapstone (Talc, Mohs 1): Perfect for intricate indoor carvings; prone to abrasion and chipping outdoors.
- Granite (Mohs 6–7): Ideal for outdoor use where durability over decades is important. Many outdoor buildings last over 100 years.
How Talc Is Used (Japan & Overseas)
Japan: Talc is popular for personal seals (inkan) thanks to easy carving; talc powder is used in cosmetics, baby powder, and pharmaceuticals.
Overseas — sculpture: Inuit soapstone carvings of seals and bears (Canada); detailed craft pieces such as the phoenix carving introduced here (China); Hindu deities, trinket boxes, accessories (India); abstract stone sculpture by the Shona people (Zimbabwe).
Other uses: Candle holders, ashtrays, trivets; stove/fireplace cladding (thermal mass); paper coating, plastic and rubber fillers (industrial talc).
Revised (New) Mohs Hardness — A Brief Note
Because Mohs steps are not equal, researchers proposed “revised Mohs” approaches that reflect actual hardness ratios. There are two common presentations: an education-friendly 15-step version (Diamond = 15) and a research-oriented extended scale (often Quartz = 100, Diamond ≈ 1500). In everyday stone descriptions and jewelry, however, the classic 1–10 Mohs remains the most widely used.
Takeaway
Mohs hardness has guided craftspeople and buyers for over two centuries. Remember it reflects surface scratch resistance, not bulk strength like compressive strength or toughness. Understanding the difference between soapstone (soft, detailed art) and granite (hard, enduring form) helps you choose the right stone for beauty, location, and longevity.
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