Gather the raw materials: sodium hydroxide, elemental sulfur, and elemental carbon
Heat the sodium hydroxide and sulfur together under controlled conditions to form sodium sulfide
Mix the sodium sulfide with carbon and heat further to produce sodium thiocarbonate intermediates
Oxidize and refine the resulting material to obtain black glassy obsidian-like silica
Melt high-silica rock or sand at very high temperature
Cool the molten silica rapidly to prevent crystal formation
Shape the cooled volcanic glass into the desired form
Polish the surface if needed