Granite and slate are both natural stones, providing popular and ideal building materials in modern constructions, particularly for tile flooring. However, granite and slate possesses quite different physical and chemical characteristics so requiring different  means of care and maintenances. Here is a comparative maintenance guide for granite and slate tiles.

Granite Tile
Mineral Composition: Quartz tile, Feldspar - varies
Hardness : Extremely Hard, second hardest only next to diamond
Absorption : Yes, Degree Varies - Oil, Water
Limitations : Absorbs oils and other acidic liquids, brittle, easy to be chipped
Suitable Sealer : Sub-surface repellents in general, oil repellent type recommended
Appropriate Cleaner: Neutral pH detergent or pure soap
Finish Sustainability: Polished and honed are most popular; Ok to apply wax

Other Maintenance issues: Granite Tile is very typical in kitchen counter and flooring applications. Sealing is strongly recommended for most granite stones. Granite Tile is the hardest polished stones commercially available and can be used in highly stressed situations. Even polished granite tile can be more absorbent to liquids than many people would think. Flamed granite tile surfaces are very absorbent due to the stress fractures in the stone formed during the flaming process and should be sealed if it is desired to maintain the original color and appearance of the stone over time.

Slate Tile
Mineral Composition: Muscovite Chlorite, wide variation in composition
Hardness : Relatively soft,  easily scratched
Absorption : Low - medium oil, water other liquids
Limitations : Absorbs certain oils and liquids, cleft planes can spall
Suitable Sealer : Sub-surface repellents oil repellent type recommended
Appropriate Cleaner: Neutral pH detergent or pure soap
Finish Sustainability : Acrylic OK, wax OK

Other Maintenance Issues: Cleft slate is very durable in most cases but overall quality may vary. Slate is typically rustic in appearance but some milled or smooth products are available in some varieties. Wear is typically taken on the peaks or high spots of the textured surface. Acrylics are used when a highly reflective finish is desired. Excellent exterior paving stone. Higher absorbency varieties may not be suitable for exterior areas in freezing climates.

Slate characteristics vary with quarry source. Domestic slate in North America is typically black, green or mottled (e.g., Pennsylvania slate) and is
relatively dense. Many imported slates are available today with wide ranging physical characteristics and overall suitability. Evaluate your stone for density, tensile strength, absorbency and abrasion resistance. Make sure the slate you are obtaining has compatible physical and chemical characteristics to the intended application.