Other

Kobellite Homologous Series Group

Koechlinite Group

Koritnigite Group

Krautite Group

Ktenasite Group

Kyanite

Hardness: 4.5 to 7

Labradorite

Hardness: 6 to 6.5

Labuntsovite Supergroup

Langbeinite Group

Lapieite Group

Gem

Lapis Lazuli

Hardness: 5 - 6

Laterite

Hardness: 1-3

Latiumite Group

Laueite Supergroup

Lava

Hardness: Variable

Lava Rock

Hardness: 5 to 6

Lavendulan Group

Lawrencite Group

Lawsonite Group

Lazulite Group

Leifite Group

Leonite Group

Leopard Skin Jasper

Hardness: 6.5-7

Lepidolite

Hardness: 2.5 - 3

Leucophosphite Group

Lillianite Homologous Series Group

Limonite

Hardness: 4 - 5.5

Linarite-chenite Group

Lindackerite Supergroup

Lithium Amphibole Subgroup

Litidionite Group

Löllingite Group

Lovozerite Group

Ludlamite Group

Ludwigite Group

Magnesium

Hardness: 2.5

Magnetoplumbite Group

Malachite

Hardness: 3.5 - 4

Marcasite Group

Margarosanite Group

Marokite Supergroup

Matlockite Group

Mayenite Supergroup

Mckelveyite Group

Melanterite Group

Melilite Group

Melonite Group

Melted Aluminum

Hardness: 2.5 - 3

Meneghinite Homologous Series Group

Metamorphic

Metavariscite Group

Meteorite

Hardness: 5.5 - 7

Mica Group

Mica Schist

Hardness: 2.5 - 4

Minasragrite Group

Minerals

Mitridatite Group

Mixite Group

Mohawkite

Hardness: 3 - 3.5

Molybdenite Group