# Tumbled rocks identification: how to tell common tumbled stones apart Source: https://tumblegrit.com/blog/tumbled-rocks-identification Published: 2026-10-12 Publisher: Tumble Grit Most tumbled rocks can be identified by four things: color and pattern, whether light passes through (translucency), luster, and a few simple tests for hardness, streak and magnetism. Nearly every mixed bag draws from the same 20 or so stones, so learning those covers most of what you will find. The sections below group them by color, then show the tests that settle the look-alikes and how to spot dyed stones and glass. ## Pinks, purples and clear stones: the quartz family Rose quartz is pale to medium pink, cloudy and translucent, never banded. Amethyst is purple quartz, often with white or clear zones and color in bands or patches. Clear quartz looks like cloudy glass when tumbled. Smoky quartz is translucent brown to gray. Citrine is translucent yellow to orange; much of the citrine sold in mixes is heat-treated amethyst, which tends to be a burnt orange with white bases. All of these are around Mohs 7: they scratch a glass plate easily and are not scratched by a steel knife. That test alone separates them from pink calcite, fluorite and dyed stones that look similar. Rhodonite is also pink, but opaque with black veins of manganese oxide, and rhodochrosite has wavy pink and white bands and is much softer, around Mohs 3.5 to 4. ## Greens and blues Green aventurine is a quartz with tiny mica flakes that glitter when you tilt it in light; that sparkle is the giveaway. Amazonite is a blue-green feldspar, often with fine white streaks in a grid pattern. Bloodstone is dark green chalcedony with red spots. Moss agate is translucent with green or black branching inclusions. Unakite mixes salmon pink feldspar and pistachio green epidote. Malachite is opaque green with bands in light and dark green; it is soft, about Mohs 3.5 to 4, and its dust should not be breathed. In blues, sodalite is deep blue with white veins and patches and almost never shows metallic flecks. Lapis lazuli is a more even, deeper blue with gold-colored pyrite flecks and sometimes white calcite. Blue lace agate is pale blue with fine lacy bands. Fluorite comes in purple, green and blue, often banded, and feels slightly greasy; at Mohs 4 a knife scratches it and it chips along flat cleavage planes. [See tumbled stone bags with named stones](https://tumblegrit.com/best/best-tumbled-stones) ## Reds, browns, blacks and the agate vs jasper question Agate and jasper are both microcrystalline quartz around Mohs 7, and they are the most common stones in any mix. The quick rule is light: hold the stone up to a flashlight. Agate is translucent, at least at the edges, and usually banded. Jasper is opaque, with no light passing through, and is often red, yellow, brown or patterned. Carnelian is translucent orange to red chalcedony, so it sits on the agate side of that test. Tiger's eye shows golden brown parallel bands that shift as you turn it, an effect called chatoyancy; red tiger's eye is heat-treated. Black obsidian is volcanic glass: glassy luster, conchoidal fractures, and softer than quartz at about Mohs 5 to 5.5, so quartz scratches it. Snowflake obsidian has white spots, and Apache tears are translucent when held to light. Polished hematite is silver-black and noticeably heavy, but tumbled stones sold as hematite are often a man-made magnetic material; real hematite is only weakly magnetic or not at all, and it leaves a red-brown streak. [Tumble your own agates](https://tumblegrit.com/best/best-rock-tumbler-for-agates) ## Five simple tests that settle most cases Hardness: try to scratch a glass bottle or plate with an edge of the stone. Quartz, agate, jasper, aventurine and tiger's eye scratch glass. Obsidian, fluorite, calcite, malachite, howlite and most dyed or glass imitations do not. Try a steel knife or nail on an inconspicuous spot: it will not scratch quartz-family stones but will scratch fluorite, calcite and howlite. Streak: rub the stone on the unglazed back of a ceramic tile. Most tumbled stones leave a white streak or none, but hematite leaves red-brown and pyrite leaves greenish black. Light: a flashlight behind the stone sorts translucent from opaque. Magnet: a small strong magnet sticks to the man-made magnetic hematite and to magnetite. Loupe: a 10x magnifier shows the mica sparkle in aventurine, pyrite in lapis, and bubbles in glass. Weight also helps. Hold two stones of similar size: hematite and some metal ores feel much heavier than quartz, while glass and plastic fakes feel about the same or lighter. ## Dyed stones and glass imitations Dyed stones are common in cheap mixes. Howlite is white with gray veins and is often dyed blue to imitate turquoise or other colors; the dye collects in the veins and cracks, so the color looks darker along them. Dyed agate in bright pink, blue or purple is usually obvious because the colors do not occur naturally in agate. A cotton swab with acetone on a hidden spot will often lift dye. Glass is the other trap. Opalite is a man-made glass with a milky blue glow. Goldstone is glass with copper flakes, sparkly and uniform. Cherry quartz and many brightly colored quartz pieces are glass, and show round gas bubbles under a loupe. Glass also feels warmer to the touch than real quartz, and it does not scratch hard glass well. None of these is a bad buy for crafts, but they should not go in a collection under a mineral name. ## Frequently asked questions Is there an app that identifies tumbled rocks? Photo apps can give a good first guess for common stones, but they struggle with tumbled pieces because the surface shape and polish hide the natural crystal form. Confirm the guess with the hardness, light and magnet tests above. How can I tell if a tumbled stone is real? Check whether it scratches glass, look for bubbles under a loupe, and see whether color concentrates in cracks. Real quartz-family stones scratch glass, feel cool, and have color through the body of the stone. What is the most common tumbled stone? Quartz-family stones dominate: agate, jasper, rose quartz, amethyst, clear quartz, aventurine and tiger's eye make up most commercial mixes, because they are abundant, hard and take a high polish. Why does my tumbled stone look different wet? Water fills fine scratches and pores, so a stone looks the way it would with a perfect polish. If it looks much better wet than dry, it is either porous or the polish is incomplete. ## Gear guides for this topic - https://tumblegrit.com/best/best-tumbled-stones - https://tumblegrit.com/best/best-rough-rocks-for-tumbling - https://tumblegrit.com/best/best-rock-tumbler-for-agates