mineral
Moonstone with Black Tourmaline (Spiderweb Moonstone)
Feldspar (KAlSi3O8) with Schorl (NaFe3Al6(BO3)3Si6O18(OH)4)
Hardness: 6-6.5 (Mohs scale); Color: Creamy white to grey with black web-like inclusions; Luster: Vitreous to pearly; Crystal structure: Monoclinic/Triclinic; Cleavage: Two directions at 90 degrees; SG: 2.56-2.59.
- Hardness
- 6-6
- Color
- Creamy white to grey with black web-like inclusions
- Luster
- Vitreous to pearly
Identified More mineral →
Explore Moonstone with Black Tourmaline (Spiderweb Moonstone) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Creamy white to grey with black web-like inclusions; Luster: Vitreous to pearly; Crystal structure: Monoclinic/Triclinic; Cleavage: Two directions at 90 degrees; SG: 2.56-2.59.
Formation & geological history
Formed in pegmatites and metamorphic rocks through slow cooling of magma, allowing the silica-rich feldspar to crystallize. The 'spiderweb' veins are caused by the intrusion of Tourmaline or other dark minerals during secondary geological events.
Uses & applications
Predominantly used for ornamental purposes, decorative obelisks, jewelry (cabochons), and by mineral collectors for its unique aesthetics and metaphysical associations.
Geological facts
Many specimens labeled as 'Spiderweb Moonstone' are actually varieties of Microcline or Orthoclase feldspar. The visual contrast between the pale matrix and dark inclusions is highly sought after in modern lapidary arts.
Field identification & locations
Identify by its distinctive play of light (adularescence) and the vein-like dark inclusions. Commonly sourced from Madagascar, India, and Sri Lanka. Collectors should look for polish quality and the contrast of the 'webbing'.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock