Starry Night Obsidian Identification Guide

What Starry Night Obsidian Looks Like

Starry night obsidian is a variety of obsidian (natural volcanic glass, essentially amorphous silica with dissolved gases) with a black to very dark gray body scattered with small pale spots that resemble distant stars. Those spots are spherulites, tiny radial clusters of cristobalite (a silica polymorph) that crystallized as the glass cooled. The base is glassy with a high vitreous luster, conchoidal fracture, and translucency to brownish on thin edges or when backlit.

Step-by-Step Field ID

1. Check the luster and break. Obsidian has a bright, glassy shine and breaks with smooth, curved, shell-like conchoidal surfaces and sharp edges.
2. Backlight it. Thin edges often glow brown or gray; true obsidian is glass, not stone.
3. Test hardness. It scratches with a steel knife only with difficulty and barely marks glass (Mohs ~5-5.5), softer than quartz-based stones.
4. Look at the "stars." Small whitish-gray rounded spherulites, sometimes with a faint radial structure under a loupe.
5. Feel the weight. Relatively light for a glassy stone (SG ~2.35-2.6).

Key Diagnostic Tests

• Mohs hardness: ~5-5.5; will NOT readily scratch glass (separates it from agate/jasper at 6.5-7).
• Streak: white.
• Fracture: conchoidal, razor-sharp edges, no cleavage.
• Specific gravity: ~2.35-2.6, noticeably lighter than crystalline silica.
• Texture: homogeneous glass, no visible crystal grains except the spherulite spots.

Common Look-Alikes

• Snowflake obsidian: essentially the same idea, but the spots are larger, whiter "snowflakes"; starry night has finer, sparser star-like flecks. Both are obsidian.
• Starry night jasper: jasper is harder (Mohs 6.5-7), fully opaque, scratches glass, and is crystalline silica, not glass.
• Black glass (slag/manufactured): can mimic obsidian but often shows perfectly round air bubbles and uniform color; natural obsidian shows flow banding and irregular spherulites.
• Apache tears / black onyx: Apache tears are obsidian nodules (translucent, no star spots); black onyx is dyed chalcedony, harder and opaque.

Where It Is Found

Obsidian forms from rapidly cooled, silica-rich (rhyolitic) lava at volcanic margins. Spherulite-bearing material comes from obsidian flows in the western United States (Oregon, Arizona, California), Mexico, and other young volcanic regions.