SecondLife Minerals
SLM-GR

SecondLife Mineral Grit

A hard angular mineral grit, nominally 14 mesh to 3/16 inch. Melt-formed, not expanded and not fired.

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A cone-shaped pile of small, hard, angular black grit particles on a plain pale background.
AI-generated illustration · Shows the form and size class of this material. Not a photograph of supplied material.

What it is

Size band
Nominal 1.4 mm – 4.75 mm as separated. Not yet sieve-tested.
Shape
Angular, hard, dry and unwashed.
Colour
Black to grey.
Plant stream
Screening overs
Structure
Amorphous, non-crystalline. The granted US patent covering the material characterises it as greater than 99% amorphous glass.
Parent specific gravity
2.7 – 2.9. This is a dense mineral glass, not a lightweight expanded material with closed internal cells.
Supplied
Loose bulk, pickup from Wabash, Indiana

What this kind of material is used for

Coarse inorganic grit in this size range is generally used for the purposes below. We are not publishing comparative performance against perlite, pumice, granite grit or calcined clay, because the tests that would support such a comparison have not been run.

  • Drainage and aeration components in growing-media blends
  • Topdressing on containers and beds
  • Bonsai, cactus, succulent and orchid substrate blends
  • Green-roof and engineered-substrate components
  • Anti-skid grit where an angular hard particle in this size range is specified

Who buys it

  • Potting soil and substrate blenders
  • Hydroponic and vertical-farm operators
  • Bonsai, succulent, cactus and orchid nurseries
  • Green-roof substrate manufacturers
  • Municipal and county buyers of winter anti-skid material

Not established yet

One of these is the most important unknown in the whole product line. It is first on the list for that reason.

  • No pH or electrical conductivity data. With 25 to 35% calcium oxide in the parent chemistry, a high initial pH is a real possibility. Until a saturated media extract pH and EC with a buffer curve are run, no statement can be made about how this material behaves in a root zone, and no grower should assume it is neutral.
  • No air-filled porosity, water-holding capacity or bulk density measurements.
  • No seed-germination or phytotoxicity bioassay.
  • No comparison against perlite or pumice. Note that at a specific gravity of 2.7 to 2.9 this material is many times denser than perlite, so a price per ton is not comparable to a price per cubic foot.
  • No durability or crush testing through wet and dry cycling.
Questions buyers ask

About Mineral Grit

What is the pH?

We do not know yet, and it matters enough that we will not guess. The parent chemistry carries 25 to 35% calcium oxide, so a high initial pH is plausible. Saturated media extract pH and EC testing is scheduled. Until it is done, treat the pH as unknown and test it yourself on a sample.

Can this replace perlite?

We are not making that claim. Perlite is a lightweight expanded material; this is a dense mineral glass at a specific gravity of 2.7 to 2.9. It will not float, and it will add weight rather than reduce it, which may be what you want or may not. Growers buy by volume, so compare cost per cubic foot rather than per ton.

Will it break down into dust?

It is a hard, dense mineral glass rather than an expanded material, but no wet-dry cycling or crush test has been run on this grit. If durability in a media blend matters to you, that is exactly what a sample should be tested for.

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