igneous
Likely labradorite-bearing pebble; the label also says “carnelian,” but that identification is uncertain
Labradorite, a plagioclase feldspar: approximately (Ca,Na)(Al,Si)₄O₈
AI-generated identification · may be incorrectA smooth gray pebble with muted rusty-red patches; no clear labradorescence is visible, so the photo alone cannot confirm labradorite or carnelian. Labradorite has Mohs hardness 6–6.5, a triclinic crystal structure, vitreous luster, and two cleavages;…
Identified More igneous →
Explore Likely labradorite-bearing pebble; the label also says “carnelian,” but that identification is uncertain in the encyclopedia →Identify your own rocks.
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Physical properties
A smooth gray pebble with muted rusty-red patches; no clear labradorescence is visible, so the photo alone cannot confirm labradorite or carnelian. Labradorite has Mohs hardness 6–6.5, a triclinic crystal structure, vitreous luster, and two cleavages; carnelian is chalcedony (SiO₂), hardness 6.5–7, with no visible crystal grains.
Formation & geological history
Labradorite commonly crystallizes in cooling magma, especially in gabbroic rocks; carnelian forms when silica-rich fluids deposit microcrystalline quartz. The specimen’s source and age cannot be determined from the photograph.
Uses & applications
Labradorite and carnelian are used for beads, cabochons, and decorative objects; feldspar is also an industrial ceramic and glass ingredient.
Geological facts
Labradorite may show vivid blue-green or gold iridescence when light hits internal layers at the right angle; none is apparent here.
Field identification & locations
The rounded shape suggests a water-worn pebble, but the gray color is not typical of carnelian. Near 30.1°N, 95.8°W, sedimentary deposits are regionally more plausible than a local labradorite source; the pebble may have been transported. Check for flash under angled light and compare a fresh, unpolished surface before identifying it.
