Earth Record
Mineralogy and formation
Amazonite with smoky quartz forms in granite pegmatites where both minerals crystallize from the same cooling melt. The amazonite (green microcline feldspar) gets its color from lead substituting for potassium in the crystal structure, combined with water molecules stabilizing the color center. The smoky quartz grew in the same pocket, its brown-to-gray color created by natural radiation from surrounding radioactive minerals (typically uranium or thorium) altering aluminum impurities in the silica framework.
Colorado's Crystal Peak area is the type locality for this combination, where collectors find both minerals intergrown in miarolitic cavities.
Chemical FormulaAmazonite: KAlSi3O8 (potassium feldspar / microcline variety) + Smoky Quartz: SiO2Crystal SystemMixedMohs Hardness6.5Specific GravityAmazonite: 2.56-2.58; Smoky Quartz: 2.65LusterAmazonite: Vitreous to pearly on cleavage; Smoky Quartz: VitreousColorGreenIMA StatusrockIMA Numberpre-IMA (grandfathered) Colorado (USA)BrazilMadagascar
Telling it apart
Amazonite with smoky quartz is not a separate species, and the main confusion is sellers presenting it as a rare named crystal rather than a natural association of two common pegmatite minerals. The cleanest test is to identify both parts separately: amazonite is blue green microcline with Mohs 6 to 6. 5 and cleavage near 90 degrees, while smoky quartz is brown gray quartz at Mohs 7 with no cleavage and conchoidal fracture.
Real specimens show a clear physical boundary between blocky feldspar and glassy smoky quartz. The amazonite section is usually opaque to translucent, greener, and more matte on cleavage faces. The smoky quartz section is more transparent, darker, and develops pointed or irregular quartz growth surfaces instead of feldspar blocks. Uniformly colored carvings sold under this name are not the same thing at all.
If every surface feels polished and the two minerals are impossible to distinguish, assume the trade name is doing all the work. Handling risk makes this important because the value sits in the natural pegmatite association and crystal aesthetics, not in an invented identity that inflates the price.
Spotting the real thing
Same tests as amazonite quartz: verify the natural intergrowth of green feldspar and brown quartz. Check for flat glue lines between components (indicates assembly). Natural specimens from Pikes Peak show both minerals with natural crystal faces.
The smoky color should penetrate the quartz, not be surface-applied.
Cross-referenceMindat ↗