ForMatter/Materials/gemstone/Smoky Quartz
mat_gem_quartz_smoky

Smoky Quartz

quartz (SiO₂) irradiation-colored, brown to gray · smoky quartz, morion (very dark), cairngorm (Scottish historical)
highlast updated 2026-04-27
metallic 0.00
hue shift +0°

Quartz colored brown to nearly black by natural ionizing radiation acting on aluminum impurities — the irradiation creates color centers that absorb across the visible spectrum. Common, inexpensive, and often used in larger statement-piece sizes where the dark transparency reads as more sophisticated than common faceted stones in pale colors.

SiO₂ in trigonal crystal system, Mohs 7. Color from [AlO₄/h⁺] color centers — substitutional Al³⁺ paired with positive holes generated by natural γ-irradiation. Specific gravity 2.65. Refractive indices 1.544 / 1.553. Heat treatment above 250 °C bleaches color reversibly via re-irradiation; the irradiation step in the trade is well-established and disclosed.

mechanical

  • mohs_hardness7
  • specific_gravity2.65
source: GIA

optical

  • refractive_index_omega1.544
  • refractive_index_epsilon1.553
source: GIA

Sustainability

  • embodied carbon kg co2e per carat0.4
  • recyclabilityhigh
  • biodegradableFalse
  • localityprimary mining: Brazil, Madagascar, Switzerland (Alpine), Scotland (historical)
visual
warm gray-brown, very dark variants nearly opaque

PBR starter values

Principled BSDF defaults derived from the sphere crystalline finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material.

# finish:      crystalline
albedo        #5a4a3a
metallic      0.00
roughness     0.05
ior           2.42
transmission  1.00
clearcoat     0.00
sheen         0.00
anisotropic   0.00
copy as JSON 
{
  "albedo": "#5a4a3a",
  "metallic": 0.0,
  "roughness": 0.05,
  "ior": 2.42,
  "transmission": 1.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}
Blender 4.x Python 
# Blender 4.x — Principled BSDF
# Smoky Quartz · finish: crystalline
import bpy
mat = bpy.data.materials.new(name="mat_gem_quartz_smoky")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.1022, 0.0685, 0.0423, 1.0)
bsdf.inputs["Metallic"].default_value           = 0.000
bsdf.inputs["Roughness"].default_value          = 0.050
bsdf.inputs["IOR"].default_value                = 2.420
bsdf.inputs["Transmission Weight"].default_value = 1.000
bsdf.inputs["Coat Weight"].default_value        = 0.000
bsdf.inputs["Sheen Weight"].default_value       = 0.000
bsdf.inputs["Anisotropic"].default_value        = 0.000
KeyShot Python (lux) 
# KeyShot 11+ — lux Python API, Generic material
# Smoky Quartz · finish: crystalline
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_gem_quartz_smoky", materialType="Generic")
mat.setProperty("diffuse",      (90, 74, 58))   # 8-bit sRGB
mat.setProperty("metallic",     0.000)
mat.setProperty("roughness",    0.050)
mat.setProperty("indexOfRefraction", 2.420)
mat.setProperty("transparency", 1.000)
mat.setProperty("coatingWeight", 0.000)
Substance pbrMetalRough 
{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "Smoky Quartz \u00b7 finish: crystalline",
  "baseColor": {
    "r": 0.1022,
    "g": 0.0685,
    "b": 0.0423
  },
  "metallic": 0.0,
  "roughness": 0.05,
  "ior": 2.42,
  "opacity": 0.0,
  "anisotropyLevel": 0.0,
  "_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}
glTF 2.0 Metallic-Roughness 
{
  "asset": {
    "version": "2.0",
    "generator": "ForMatter"
  },
  "materials": [
    {
      "name": "mat_gem_quartz_smoky",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.1022,
          0.0685,
          0.0423,
          1.0
        ],
        "metallicFactor": 0.0,
        "roughnessFactor": 0.05
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 2.42
        },
        "KHR_materials_transmission": {
          "transmissionFactor": 1.0
        }
      }
    }
  ]
}
USD Preview Surface 
# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Smoky Quartz · finish: crystalline
def Material "mat_gem_quartz_smoky" {
    token outputs:surface.connect = </mat_gem_quartz_smoky/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.1022, 0.0685, 0.0423)
        float   inputs:metallic     = 0.000
        float   inputs:roughness    = 0.050
        float   inputs:ior          = 2.420
        float   inputs:opacity      = 0.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}
↓ download glTF material
Substitutes
Amethyst
Citrine

Citations