Q1 Q2 rhyolite dacite quartztrachyte quartzlatite trachyte latite alkali feldspar rhyolite andesite (M<35%) 60 20 10 35 65 5 Q A P IUGS ClassificationVolcanic/Aphanitic Rocks2a. Volcanic rocks with quartz Q = quartzA = alkali feldsparP = plagioclase feldspar Q1. alkali feldspar trachyteQ2. quartz alkali feldspar trachyte
Mafic Mineral %   


IUGS Chart 2c. QAP. IUGS diagram for naming volcanic/aphanitic igneous rocks with quartz present. Names are based on the relative modal proportions of quartz (Q), alkali feldspar (A), and plagioclase feldspar (P). Use the Mafic Mineral percentage slider to see the andesite classification change to basalt for rocks with M>35%.

For foid-bearing volcanic/aphanitic rocks click here:
For the full IUGS QAPF Volcanic chart click here: