Technical Data

Technical Data

Technical Data

Technical Data

Commitment to Excellence

There are many factors that play a role in creating the specialty aggregates, natural thin stone veneer, and other products that Kafka Granite manufactures. Our decades of experience in the industry have made it clear to us that architects, designers, stonemasons, and others need high-quality specialty aggregates and masonry units that will hold up under stress and against natural forces. Kafka performs various testing methods on their materials to ensure the product is suited to your project specifications. To further demonstrate our commitment to transparency and quality, all test data is available to our customers.

When you purchase specialty aggregates and other natural stone products from Kafka Granite, you can rest easy knowing the materials you receive will be of the highest quality. Contact us today to learn more about our material testing and specifications.

Specific Gravity

Kafka Granite adheres to ASTM material specifications for our stone products. Samples of our specialty aggregates are sent out for a number of tests, including ASTM C127: Standard Test Method for Specific Gravity and Absorption of Coarse Aggregate. This particular assessment determines the density of a given aggregate. This data can help determine whether the crushed stone is appropriate for a specific application.

Specific gravity is a ratio of the mass of a substance to the mass of the same volume of liquid (typically distilled water). As water is the typical standard, it is understood to have a specific gravity of 1. A specific gravity below 1 indicates that a substance is less dense than water and will therefore float in the liquid, while a specific gravity greater than 1 means that the substance is more dense and will sink. Specific gravity in natural stone ranges from 2 to 3, meaning that stone is two to three times denser than water.


ASTM C127 also determines the absorption of a given aggregate. Different absorption levels determine how well a specific type of stone will withstand weathering and structural stress, and, by extension, how a product can be used. It’s essential that the qualities of a stone match the needs of the application. Absorption capacity is particularly important in natural stone products that will be exposed to the elements and undergo the freeze-thaw cycle. Absorption can also tell us about a stone’s stain resistance.

Absorption is the percent by weight increase in the mass of a material when water is absorbed into its pores. Aggregate samples are first dried to remove any excess moisture, and the density of the aggregate is measured. The samples are then soaked in water for a prescribed period to ensure that they reach maximum absorption capacity, and these soaked samples are used to determine the saturated-surface-dry density and absorption.

Mohs Hardness

The Mohs scale of mineral hardness is used to measure the scratch resistance of a material, and also aid in identifying minerals. Measurements range from 1 to 10, with 1 indicating the softest material and 10 the hardest. Depending on what the aggregate is being used for, there may be an industry specification or product standard that states how hard the stone needs to be. For example, an abrasive quality allows harder stone products to stand up to harsh environments, or allows softer stone products to polish more effectively. Sourcing stone that meets stringent specifications is no easy task, particularly if you’re searching for a particular color. Luckily, Kafka Granite offers a wide range of products with different levels of hardness.

Metal picks of varying hardness are used to scratch the surface of the material. When the material is able to be consistently scratched by a particular pick, it identifies the hardness of that material.

Sieve Analysis

The process of a sieve analysis is used to determine an aggregate’s gradation, or the distribution of stone particles by size, within a given sample. The sieve analysis is especially important to evaluate the performance of aggregates for their intended uses, and can be critical in the strength of the finished product, compaction of the aggregate, or the visual aesthetic. A sieve analysis is also helpful as a measure of quality control and consistency when crushing. Kafka produces a large range of aggregate sizes to meet nearly any size specification.

A sieve analysis starts with the stacking of sieves, or screens, from the largest to the smallest size. Bulk aggregate is placed on the top sieve and the material is screened through the various sieves, subsequently becoming separated by size. Once sifted, each sized aggregate is weighed and noted as a percentage of the overall sample — that is, the percent of aggregate retained per sieve is noted as well as the percentage passed through that size sieve (passing aggregate).


Specialty Aggregate Technical Data

Aggregate Specific Gravity Absorption Mohs Hardness Full Testing Report
Aspen Glitter 2.68 0.7% 7 PDF
Autumn Blend Marble 2.82 1.9% 5-5.5 PDF
Beige Blend Marble 2.85 0.6% 4-4.5 PDF
Birchwood Pebbles 2.83 1.1% 5-5.5 PDF
Black Diamond Granite 3.51 0.5% 6-6.5 PDF
Blue Mahogany Granite 2.69 0.6% 7-7.5 PDF
Botticino Marble 2.77 1.7% 3-3.5 PDF
Buff River Tan Pebbles 2.75 2.0% 4.5-5.5 PDF
Burnt Sienna Marble 2.79 3.0% 5 PDF
Butterscotch Pebbles 2.62 2.6% 7-7.5 PDF
Caramel Quartzite 2.58 2.0% 7.5 PDF
Cherry Creek Pebbles 2.77 1.4% 5-6 PDF
Chocolate Brown Granite 2.86 3.2% 3-4 PDF
Colonial Red Granite 2.64 0.4% 7.5 PDF
Dusty Rose Marble 2.79 0.7% 4.5-5 PDF
Dynamite Orange Granite 2.65 0.7% 7-7.5 PDF
Evergreen Granite 2.96 0.5% 3 PDF
Galaxy Glitter 2.76 0.9% 6.5-7 PDF
Golden Cream Marble 2.80 5.1% 3-3.5 PDF
Gun Metal Marble 2.86 0.4% 3.5 PDF
Imperial Gray Granite 2.67 0.5% 7-7.5 PDF
Mauve Granite 2.64 0.6% 7 PDF
Midnight Blue Granite 2.88 0.4% 7-7.5 PDF
Mint Glitter 2.74 1.6% 6.5-7 PDF
Misty Gray Marble 2.88 0.8% 2.5-3 PDF
Pewter Granite 2.78 0.8% 7-7.5 PDF
Platinum Granite 2.71 0.5% 7 PDF
Polar White Marble 2.78 0.7% 3.5 PDF
Recycled Copper Slag 3.04 0.3% 6.5-7 PDF
Recycled Mirror - - - -
Recycled Porcelain 2.46 1.8% 7.5 PDF
Recycled Smoked Glass - - - -
Red Cedar Granite 2.60 2.0% 6.5 PDF
Rosa Glitter 2.68 1.0% 7.5 PDF
Rose Pink Quartz 2.65 0.4% 7.5 PDF
Rustic Granite 2.58 1.5% 6.5-7 PDF
Salt & Pepper Granite 2.72 1.0% 6.5-7 PDF
Shamrock Green Granite 3.11 0.7% 7.5 PDF
Sierra Black Granite 2.76 0.6% 7-7.5 PDF
Snow White Granite 2.66 1.1% 7-7.5 PDF
Starlight Black Granite 2.94 0.5% 7 PDF
Sterling Quartz 2.69 0.7% 6.5-7 PDF
Sugar & Spice Granite 2.71 0.7% 7-7.5 PDF
Sunset Pink Granite 2.64 0.6% 7-7.5 PDF
Super White Marble 2.75 0.5% 4.5-5 PDF
Turquoise Marble 2.83 1.6% 3-3.5 PDF
Twilight Black Granite 2.94 0.5% 6.5-7 PDF
Violetta Quartzite 2.66 0.5% 7.5 PDF
White Quartz 2.66 0.4% 7.5 PDF
Wineberry Granite 2.68 1.5% 7 PDF
Wisconsin Pride Pebbles 2.74 0.9% 5.5-6 PDF

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