Obsidian Field Notes https://oracle.xraycs.com/ Independent notes on volcanic glass, fracture surfaces, specimen photography, and volcanic landscapes. en Sat, 25 Jul 2026 12:00:00 GMT From lava flow to hand specimenhttps://oracle.xraycs.com/notes/from-flow-to-fragment/https://oracle.xraycs.com/notes/from-flow-to-fragment/Sat, 25 Jul 2026 12:00:00 GMTThe rough volcanic landscape behind a tidy piece of obsidian. Photographing a nearly black surfacehttps://oracle.xraycs.com/notes/photographing-dark-minerals/https://oracle.xraycs.com/notes/photographing-dark-minerals/Sat, 25 Jul 2026 11:30:00 GMTA simple reflected-light method for showing luster without flattening texture. Obsidian and basalt are both dark—then the similarities endhttps://oracle.xraycs.com/notes/obsidian-and-basalt/https://oracle.xraycs.com/notes/obsidian-and-basalt/Sat, 25 Jul 2026 11:00:00 GMTComparing grain, luster, fracture, composition, and formation. What makes the “snowflakes”?https://oracle.xraycs.com/notes/snowflake-obsidian/https://oracle.xraycs.com/notes/snowflake-obsidian/Sat, 25 Jul 2026 10:30:00 GMTPale spherulites and the process by which volcanic glass devitrifies. Reading a conchoidal fracturehttps://oracle.xraycs.com/notes/conchoidal-fracture/https://oracle.xraycs.com/notes/conchoidal-fracture/Sat, 25 Jul 2026 10:00:00 GMTCurved surfaces, ripple marks, bulbs, and the absence of crystal cleavage. On edge reflections in black volcanic glasshttps://oracle.xraycs.com/notes/edge-reflections/https://oracle.xraycs.com/notes/edge-reflections/Sun, 14 Jun 2026 05:13:00 GMTA first observation about thin highlights and hidden fracture curves.