Slate can be used outdoors in patios and stairs.
Slate is a gray to dark-colored stone that is created from sedimentary rocks during the metamorphic process. This common rock usually forms in thin layers that sometimes appear at the surface of the earth. Slate is often used as roof shingles and occasionally as a tombstone. During past centuries it was used to make chalkboards and billiard tabletops. In the United States, commercially viable deposits are found in the northeastern states of Pennsylvania, New York, Vermont and Maine. Texas rock hounds sometimes collect slate in the Fredericksburg area in the south central region of the state. Does this Spark an idea?
1. Study the geological process by which slate is formed. This includes looking at shale, for most slate is formed from the metamorphosis of shale, a sedimentary rock that is common in Texas. Not all shale deposits contain slate, but on the other hand, slate is almost always created from shale.
2. Obtain a USGS geological map of the rock formations in Texas and get to know what rocks are found in some of the well-known formations. For example, the Willis formation is on a geological map, symbolized by the letters POW just north of Houston. However, since the primary geology is clay or mud it will not be of interest to the search for slate.
3. Cross reference for slate deposits or slate quarries in central Texas. Little appears on web-searches except for some existence of small amounts of slate in the Llano Uplift in Central Texas.
4. Search until you pinpoint a slate formation.The University of Texas’s Virtual Landscape of Texas webiste reports slate formations near the town of Marble Falls, in the vicinity of Fredericksburg. The reference is very obscure and only uses the term “Thin-bedded slate or slaty limestone” to describe rocks found around Marble Falls, but this is a good starting point.