What is Rock Tumbler Grit Made Of

What is Rock Tumbler Grit Made Of?

Rock tumbling is a popular hobby and lapidary process used to transform rough rocks and stones into beautifully polished gems and ornaments. A crucial component of the rock tumbling process is the use of grit, which plays a significant role in smoothing and polishing the rocks.

Here, we explore what rock tumbler grit is made of and its importance in achieving stunning polished results.

1. Understanding Rock Tumbler Grit

Rock tumbler grit is a granular substance used in the rock tumbling process to abrade and polish the rough surfaces of rocks. It aids in the progressive stages of grinding and polishing, gradually transforming the rocks from rough and uneven to smooth and shiny.

2. Components of Rock Tumbler Grit

Rock tumbler grit is typically composed of various abrasive materials, each with a specific purpose in the tumbling process. The main components of rock tumbler grit are as follows:

a. Silicon Carbide

Silicon carbide is one of the most common and essential components of rock tumbler grit. It is a hard and sharp abrasive that effectively grinds down rough edges and surfaces of rocks. Silicon carbide is available in different grades, ranging from coarse to fine, with each grade used in specific tumbling stages.

b. Aluminum Oxide

Aluminum oxide is another common component of rock tumbler grit. It is also a hard abrasive that is particularly effective in polishing the rocks, giving them a smooth and lustrous finish. Like silicon carbide, aluminum oxide is available in various grades for different tumbling stages.

Also Check: Rock Tumbler Grit Is Toxic?

c. Cerium Oxide

Cerium oxide is a specialized abrasive used primarily for polishing glass, stones, and minerals. It is especially effective in achieving a high-gloss polish on rocks and gems. Cerium oxide is often used in the final stages of the tumbling process to produce a brilliant shine on the stones.

3. Grit Sizes and Stages

Rock tumbler grit is available in different sizes, each designated for specific tumbling stages. The most common grit sizes used in rock tumbling are:

  • Coarse Grit: Typically 60/90 or 80 grit, used to shape and smooth the rough surfaces of rocks in the initial stages.
  • Medium Grit: Usually 150/220 or 180 grit, used for further smoothing and refining the rock’s shape.
  • Fine Grit: Often 500 or 600 grit, used for pre-polishing the rocks, preparing them for the final polishing stage.
  • Polishing Grit: Usually, 1200 grit or higher, used to achieve a high-gloss polish on the rocks and gems.

4. Importance of Using Grit in Rock Tumbling

Rock tumbler grit is essential in the tumbling process because it facilitates the grinding and polishing of the rocks. Without the appropriate grit, achieving the desired smooth and shiny finish would be challenging, if not impossible.

Also Check: Can I Reuse Rock Tumbler Grit?

Each stage of grit contributes to the gradual transformation of rough rocks into beautiful and polished gemstones.


Rock tumbler grit is a critical component in the process of transforming rough rocks into beautifully polished gemstones and ornaments. It consists of various abrasive materials, such as silicon carbide, aluminum oxide, and cerium oxide, each playing a specific role in grinding and polishing the rocks.

By understanding the components and sizes of rock tumbler grit, hobbyists and lapidary enthusiasts can achieve stunning results in their rock tumbling endeavors, turning rough rocks into dazzling gems.

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