What is a characteristic of the lowest quality of slate tile?

The characteristic associated with the lowest quality of slate tile is ribboning. Ribboning refers to bands of color or texture that can run through the slate, which may indicate variations in the material's composition and can affect its durability and aesthetic appeal. High-quality slate typically has a uniform appearance without such unevenness.

In lower quality slates, ribboning can result from inconsistent mining practices or inadequate processing techniques, leading to a product that may not hold up as well over time. Recognizing ribboning is essential for identifying quality, as it often suggests the slate is less durable and more prone to cracking or breaking compared to higher-grade slates, which tend to have a smoother and more consistent surface.

Surface smoothness can vary across different grades of slate; high-quality slate can also be smooth, so it's not a definitive factor of low quality. Color variation, while sometimes seen in lower-quality slate, can also be a desirable characteristic in high-quality products. Similarly, weight by itself isn't a reliable indicator of quality since both high and low-quality slates can differ significantly in mass depending on their density and thickness. In contrast, ribboning is a clear sign of compromised quality and is a critical factor when assessing slate tiles.