monoclinic Ornamental rocks
Maw-Sit-Sit
Formula Multi-mineral rock aggregate; dominant phases kosmochlor (NaCrSi2O6) + jadeite (NaAlSi2O6) + albite (NaAlSi3O8) + chromite (FeCr2O4)
Crystal Structure
#! Species: Maw-Sit-Sit (kosmochlor-jadeite rock)
#! System: Monoclinic (2/m; dominant pyroxene phase proxy)
#! Habit: Massive aggregate; vivid green with black chromite inclusions
monoclinic[2/m]:{110}@1.0 + {010}@0.5[inclusion:chromite] + {001}@0.7
monoclinic
2/m
{110} {010} {001}
Quick Facts
Hardness
6.0
Specific Gravity
3.0
Refractive Index
1.52
Optical Character
AGG
Physical Properties
- Crystal System
- monoclinic
- Hardness (Mohs)
- 6.0
- Specific Gravity
- 3.0
- Cleavage
- None (polycrystalline aggregate)
- Fracture
- Splintery to uneven
- Lustre
- Waxy to vitreous
Optical Properties
- Refractive Index
- 1.52
- Optical Character
- AGG
- Pleochroism
- None (aggregate)
Characteristics
Colours
Vivid emerald-green to bright green (kosmochlor/jadeite matrix; Cr3+ chromophore)With black to dark green spots and veins (chromite + kosmochlor-rich zones)
Localities
Myanmar (Kachin State, Tawmaw area; only commercial source)
Common Inclusions
Chromite crystals (diagnostic black to dark green spots)Albite-rich feldspar patchesKosmochlor-jadeite intergrowths
Known Treatments
Generally not treated; waxing occasionally for surface stabilisation
Crystal Forms
massive
Diagnostic Features
Vivid emerald-green matrix with black to dark green spots or streaks (chromite inclusions); Chelsea filter strongly red (Cr3+); RI aggregate reading typically 1.52-1.68 (varies by phase); SG 3.00-3.40 (heavier than jadeite 3.34 average due to chromite); Myanmar (Kachin State) as only commercial source
Notes
Multi-mineral decorative rock; NOT a single IMA mineral species. Dominant mineralogy: kosmochlor (NaCrSi2O6, a chromium pyroxene, monoclinic 2/m) + jadeite (NaAlSi2O6, monoclinic 2/m) + albite + chromite. Crystal system assigned as monoclinic (dominant pyroxene phase). First described by Gübelin 1965, Journal of Gemmology (DOI 10.15506/jog.1965.9.10.329) [VERIFIED]. Mineralogical composition confirmed by Harlow et al. 2000 (DOI 10.15506/jog.2000.27.2.87) [VERIFIED] and Ou Yang et al. 2025 (DOI 10.3390/cryst15110983) [VERIFIED]. CAUTION: This is a polycrystalline multi-mineral rock aggregate — RI, SG, and hardness are composite values depending on the mix of phases. The Chelsea filter red reaction is from Cr3+ in kosmochlor. Often confused with jadeite but the chromite spots and higher Cr content distinguish it. Not a standard jade variety.
Related Minerals
Other minerals in the monoclinic system
