Igneous and Metamorphic Rocks of the Serpentine Hot Springs Area, Seward Peninsula, Alaska

abundant Accessory minerals aggregates Alaska albite allanite anhedral anhedral grains anomalous aplite bands bedrock biotite biotite granite calcite carbonaceous carbonaceous metasedimentary rocks cassiterite ceous characteristically chlorite chlorite-muscovite-quartz schist Collier color commonly composition concentrations contain dark-gray deformed dikes discontinuous dominantly equigranular euhedral facies 3A feldspar fine-grained fluorite foliation forms geologic gneiss grain boundaries granite stock hand specimens hornfels Hot Springs area Humbolt Creek intergranular iron hydroxides K-feldspar K-feldspar crystals K-feldspar phenocrysts Kachadoorian light gray lineation lithologic units locally magnetite map area marble margin medium grained metamorphic rocks metasiltite miarolitic cavities microfolds muscovite occur Oonatut Granite Complex opaque material outcrops pegmatite percent perthitic phenocrysts plagioclase pluton porphyritic porphyroblasts present quartz rocks of zone Sainsbury schist schistose seriate seriate-textured Serpentine Hot Springs Seward Peninsula sphene structures subequant subhedral Survey Bull textural facies thermal aureole thermal metamorphism thin section thrust faults tin deposits tion tourmaline U.S. Geol variably well-developed zircon