BH250-92
Title
BH250-92
Subject
Graphic Granite
Description
Major Minerals: quartz, orthoclase
Minor Mineral: muscovite
Graphic granite is an igneous texture, not a distinct rock type, characterized by the intergrowth of quartz and feldspar, typically forming vermicular or cuneiform patterns that resemble ancient writing. This texture is most commonly found in pegmatites. It usually consists of alkali feldspar (orthoclase, microcline, or sanidine), with quartz forming the intergrown patterns; plagioclase may occasionally be present. Graphic granite forms during the slow cooling of silica-rich melts, particularly under conditions where quartz and feldspar crystallize simultaneously from a residual melt. This texture likely develops near the granite eutectic point, where both phases nucleate and grow together, and in some cases, quartz may exsolve from feldspar during cooling, enhancing the graphic intergrowth.
Minor Mineral: muscovite
Graphic granite is an igneous texture, not a distinct rock type, characterized by the intergrowth of quartz and feldspar, typically forming vermicular or cuneiform patterns that resemble ancient writing. This texture is most commonly found in pegmatites. It usually consists of alkali feldspar (orthoclase, microcline, or sanidine), with quartz forming the intergrown patterns; plagioclase may occasionally be present. Graphic granite forms during the slow cooling of silica-rich melts, particularly under conditions where quartz and feldspar crystallize simultaneously from a residual melt. This texture likely develops near the granite eutectic point, where both phases nucleate and grow together, and in some cases, quartz may exsolve from feldspar during cooling, enhancing the graphic intergrowth.
Creator
Bereket Haileab
Source
From the rock collection of Bereket Haileab. Sample BH250-92. Housed at Carleton College in Minnesota.
Type
Thin section and hand sample
Relation
Collection
Citation
Bereket Haileab, “BH250-92,” BH250 Mineralogy Teaching Collection, accessed April 25, 2026, https://bereket-haileab.geology.sites.carleton.edu/items/show/105.