| Characteristics | Value |
| Hardness | 6-7 |
| Heat Resistance | Very High |
| Acid Resistance | Good |
| Maintenance | Moderate (waterproofing required) |
| Common Uses | Countertops, internal floors, facades, external areas. |
| Reference standard 15.845/2015 |
Processing techniques for Tormenta Negra Granite
The Tormenta Negra Granite, is a medium to coarse-grained igneous rock with a bottom intense black interspersed with white and gray veins and spots, which create a storm-like movement effect, hence its commercial name.
Average Mineral Composition
- Plagioclase + Alkaline Feldspar: 40–50%
- Quartz: 20–30%
- Biotite and Hornblende: 15–20%
- Accessory minerals (iron oxides, pyroxene): up to 5%
Properties
- Hardness: 6–7 Mohs → good scratch resistance.
- •Water absorption 0.3% – 0.5% → medium porosity, pay attention to waterproofing.
- Compressive strength: >200 MPa.
- Chemical resistance: stable against weak acids and household products. Its aesthetic appeal lies in contrast of light veins on the black background, being widely used in countertops and visually impactful projects.
INFORMATION FOR FABRICATORS (Stone Workers)
Recommended Finishes
- •Polished: enhances the contrast between black and light veins, often used on countertops and islands.
- •Brushed (Leather): gives a satin and contemporary look.
- •Honed: uniform, elegant matte finish on indoor floors.
- Flamed + Brushed: ideal for outdoor areas and non-slip surfaces.
Processing and Cutting
- Rock with good workability, but with the presence of lighter veins that may be areas of greater weakness → reinforce with epoxy resin if necessary before polishing.
- Recommended discs: Diamond blade 350 mm OS–31SS or Diapar DP-1015 for high hardness granites.
- Allows for special moldings and cuts, maintaining a uniform finish.
Sealing
Due to the medium porosity and the presence of dark minerals, it is recommended to waterproof all parts.
Recommended Products:
- •Brazil: Rock Protect – Chemistone, Nano Effect – AKEMI, Idea Gold – Bellinzoni
- •International: Proseal – Tenax, Stain Proof – Dry Treat, Idea Gold – Bellinzoni
Procedure:
- •Apply on a clean and dry surface using a brush or roller.
- Also waterproof the sides of floors, skirting boards and window sills.
- Reapply every 2–3 years, depending on exposure.
Adhesive Bonding
- Use epoxy/polyester adhesives specifically for granite (Tenax Fix Top, Bellinzoni Blitz Mastique, Argacon Marmofix).
- Pigment glues in black or gray to harmonize with the background of the material.
INSTALLATION
- Countertops: support every 60 cm with metal corners; gluing with white or black PU40. Avoid industrial silicones.
- Indoor/Outdoor Floors: white or gray ACIII mortar.
- Grouting: with flexible grout, apply waterproofing after the mortar has cured.
CLEANING AND MAINTENANCE
- Routine: damp cloth and neutral detergent.
- Avoid: abrasive products or strong acids (chlorine, bleach, caustic soda).
- Post-construction: use specific cleaners (Quartzolit Pós-Obra, Bellinzoni floor cleaning detergent, PCS Alcalino – Piso Clean).
FINAL CONSIDERATIONS
The Tormenta Negra Granite is a material of strong aesthetic appealvisual movement resistance and visual exclusivity. Ideal for kitchen countertops, gourmet areas, interior floors and exterior facades, conveys sophistication with personality. Its main concern is adequate waterproofing, ensuring longevity of the black color and preserving the light veins.
