M-DISC™: YOUR LIFE. ENGRAVED IN STONE.
Rock-Like?
The phrase “rock-like” is used to describe the M-DISC™ data layer, yet the disc is obviously not madeof rock. So why is this description appropriate? Is this more than a clever marketing ploy? The answer isyes, much more. The M-DISC™ data layer has several properties comparable to those of common rocks.
The composition of the data layer, its morphology, and the changes it undergoes during the data-writing
process all present intriguing parallels to rock. Rocks are composed of inorganic materials that are typicallyoxides of metals and metalloids. Common compounds found in rocks include silicon dioxide, aluminumoxide, alumino-silicates, and more. Many more complex compounds are also common, including elements
such as carbon, nitrogen, potassium, calcium, iron and other metals, and so on. All of these compounds are
solid from well below room temperature to upwards of a thousand degrees Celsius in most cases, and they
are all chemically stable against oxidation, the effects of water, and other corrosive or aggressive chemicalenvironments.

The Inorganic Data Layer
The M-DISC™ data layer has many of the same characteristics.
It is composed entirely of inorganic materials and compounds
including metals and metalloids. It contains several of the materials
and compounds common to rocks including oxides of silicon andrare-earth metals. It is a solid from room temperature to upwards of500°C, and it is stable in the presence of oxygen, nitrogen, water,and other deleterious chemicals that may be found in ordinarystorage environments.

Data Layer Physical Structure
The M-DISC™ morphology, or physical structure, also has characteristics analogous to common rocks. It includes
multiple layers of dissimilar materials, like common sedimentary and some igneous rocks. The comparison
even makes sense on the microscopic scale, where the written M-DISC™ can be described as an aggregate ofordered, polycrystalline regions and amorphous or glassy regions. The engraved “pits” in the M-DISC™ that
hold the digital data are also like the void structures that can be found in many igneous rocks such as pumiceor scoria.

Engraving Data in Stone
Finally, the inorganic M-DISC™ data layer materials undergo physical change during the write process in thesame way that rock materials change under the influence of heat and other geologic processes. When the datalayer is written by a focused laser, the intense heat generated causes the innermost layers to melt and to moveaway from the laser spot, creating a hole in the data layer. The materials found in rocks would react to the laser
in a similar way, melting, flowing or ablating away, in contrast with the organic dyes used in typical Blu-rays andDVDs, which would merely decompose under the same thermal conditions. Furthermore, when the melted
portions of the M-DISC™ data layer cool after writing, the material surrounding the written voids forms apolycrystalline structure that is again reminiscent of the microcrystalline structure of many common rocks.

Permanent by Design
In summary, a comparison of the M-DISC™ data layer to natural rock is valid on many points. This is not byaccident. The intent of the scientists and engineers who developed the M-DISC™ was to develop the modern
digital equivalent of engraving in stone. The characteristics and features that enable a rock to survive
for tens of thousands of years without change were the inspiration behind the product. It isn’t bychance that the M-DISC™ data layer is similar to a rock — it’s by design.

M-DISC

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