igneous
Diorite (Spotted or Dalmatian Stone effect)
Diorite (Intermediate Plutonic Rock)
Hardness: 6-7 (Mohs scale); Color: Black and white 'salt and pepper' appearance (mottled); Luster: Phaneritic (crystalline) to dull; Crystal structure: Phaneritic, medium-to-coarse grained; Cleavage: Good in two directions via feldspar; Specific gravity: 2.8-3.0.
- Hardness
- 6-7 (Mohs scale)
- Color
- Black and white 'salt and pepper' appearance (mottled)
- Luster
- Phaneritic (crystalline) to dull
Identified More igneous →
Explore Diorite (Spotted or Dalmatian Stone effect) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Mohs scale); Color: Black and white 'salt and pepper' appearance (mottled); Luster: Phaneritic (crystalline) to dull; Crystal structure: Phaneritic, medium-to-coarse grained; Cleavage: Good in two directions via feldspar; Specific gravity: 2.8-3.0.
Formation & geological history
Formed by the slow cooling of magma beneath the Earth's surface in volcanic arcs and at subduction zones above convergent plate boundaries. It is primarily composed of plagioclase feldspar and hornblende or biotite.
Uses & applications
Used as a decorative crushed stone or 'dimension stone' for building facades, floor tiles, and countertop surfaces. Historically used in ancient sculptures, such as the Code of Hammurabi, due to its durability.
Geological facts
Diorite is often called the 'Salt and Pepper Rock' because of the stark contrast between its dark and light minerals. While common, exceptionally smooth river-polished stones like this one are popular among hobbyists as 'worry stones'.
Field identification & locations
Identify in the field by its speckled texture and lack of visible quartz (unlike granite). Commonly found in the roots of mountain ranges (plutons). Collectors should look for balanced distribution of black and white minerals with a high degree of natural river polishing.
