What Are Quarries and What Do They Do?

In general terms, a quarry is a mining operation whose purpose is to extract raw material from the Earth for use or processing. Specific to Twisted Nail, an aggregate quarry is a quarry variation used to extract stones, rock, dirt, sand, and other aggregates that will be repurposed into building materials. Aggregate quarries belong to a subgroup of quarries called open pit mines. These mines are open to the earth’s surface and do not function below the ground, all activity is performed above ground. While there are many types of quarries that supply a wide range of products, aggregate quarries exist to dig up and process any stone-related materials that are used in construction. Texas has many quarries in general but has a significant number of aggregate quarries when compared to other states.

What Are the Most Common Materials Found in Texas Quarries?

The most common quarry type in Texas is the aggregate quarry, which specializes in stone, gravel, sand, and fill dirt. While these quarries are similar to like-kind quarries in other states, Texas has a large number of quarries that make construction aggregates readily available in most regions of the state. To further categorize these aggregate quarries, we can break down the types of aggregate they produce into these main categories: sand, fill, rock, and stone.

What Are Sand and Gravel Quarries?

Simply put, sand and gravel quarries are mines that are purposed for extracting sand and gravel from the Earth. While a quarry can be a mixture of sand, gravel, rock, and stone it is more common for a quarry to specialize. Sand and gravel quarries specialize in loose aggregates like various types of construction rock, sand, and fill dirt materials. In Central Texas, these quarries produce two main types of rock: river rock and limestone. Both river rock and limestone quarries will also produce select fill, common fill, washed sand, and various construction rocks ranging from crusher fines, 3/8”-1” rock, 2”-6” bull rock, and 6”-36” rip rap. Some materials are much more common, such as common fill, pea gravel, sand, and top soil; however, some materials, like silica sand and #57 rock, are exceedingly rare and often require import from other regions of the state. Application of these materials can be varied and the available use-cases are nearly endless. Most commercial projects will require a combination of select fill, state spec road base, ¾”-1” rock (#57 Rock), and rip rap with some projects requiring specialty materials depending on the projects requirements. For residential projects, the most commonly used materials include flexbase, pea gravel, 1” river rock, oversized river rock, common fill, and top soil.

Fill Materials

Common Fill and Select Fill

Fill dirt is available in two main types: common fill and select fill. While both are made of a mixture of sand and clay, common fill is not bound by any testing metrics and can be delivered as any combination of the two materials. Select fill, however, implies that the material is tested and will conform to a standard composition of sand and clay. Common fill is an affordable option for many smaller residential projects, such as building an RV pad, but would not be a good material to use where long-term stability is a concern, such as a new home build. For long-term performance contractors and homeowners should defer to select fill, which will have an approved consistency and will perform better over time.


Topsoil is considered a category of fill dirt and is used in areas seeking to cultivate plant life, such as gardens or lawns. It is placed above all other fill dirt to help nourish the land, but can also be used on its own. Topsoil is a popular choice for landscaping projects.

Silica Sand

Silica sand is exceedingly rare in Texas, so is much more expensive than other types of sand. However, while rare, it is still possible to source from within the state. Silica sand comes in a beautiful white color that is the result of quartz being broken down through erosion. Because of its price, it is most often used in specialty industrial projects as well as artificial beaches, golf courses, and for filtration.

Washed Sand

Washed sand, also called concrete sand, is sand that has been processed through a series of screening and washing to remove impurities before being used for construction purposes. Washed sand is used in concrete applications as an additive to make concrete, for walkways, in golf courses, pool construction, patio builds, and other leveling projects. The material comes in an off-white color and is a key ingredient in concrete production, along with a coarse aggregate, cement, and water.

Limestone Materials

Limestone Base (State Spec or Flexbase)

Most construction projects in Texas utilize limestone base in some capacity. Base is a mixture of rock and dirt (fines) that hardens after getting wet. The material composition can vary. Limestone flexbase is often used in residential projects such as country roads, driveways, or as pads for a shop or RV. Because flexbase does not require testing it can come in unpredictable compositions, with some batches delivered with more rock and others with more fines. State spec base, however, is regulated to a very specific combination and should always be delivered with a consistent composition. This composition is defined by the state and allows the material to be used in commercial applications. The material is widely available in Texas and is often found to be one of the cheaper material options available.

Crusher Fines

Crusher fines are a budget material that are a byproduct of the crushing process limestone must go through. Crusher fines are small in size, ranging from dust to 3/8” in diameter, and can function similar to road base depending on the materials composition. While not recommended for most commercial projects, crusher fines can be an excellent alternative to road base for non-foundation residential projects that are budget conscious. The material can be an excellent choice for country roads, pathways, driveways, RV pads or other casual projects requiring a little stability.

Crushed Rock

Crushed rock is a foundational aggregate in almost all construction projects. Crushed rock can come in untested and tested variations, with untested materials not conforming to any state specifications and tested versions conforming to very specific sieve tests to ensure uniformity in the material being delivered. This type of aggregate will range in size and can be anywhere from ¼” to 2” in size. Two common terms associated with crushed rock are screened and washed, referring to the material being processed through a screen (and therefore all non-conforming sizes filtered out) and washed referring to the material being cleaned of any sediment that is attached to the rocks after being mined. The popularity of crushed rock in construction uses can make this material very difficult to find and very expensive to purchase. ¾” Rock – 1” Rock, otherwise known as #57 rock, is an excellent example of this. This size rock, particularly in the washed variant, is used in almost all commercial earthwork projects and is a required additive for concrete production. The material is often easy to find in some capacity, but will frequently need to be imported if the project is not flexible on size or washed/unwashed requirements.

Bull Rock

Bull Rock is limestone that is a step up in size from crushed rock, typically ranging from 2” in size to 6” in size. This rock is frequently used as a filter material or as a stabilizer on construction projects. The most commonly available bull rock is a 3”x5” rock, aka 3×5 or 3 by 5, and is used to create a stable entrance on construction projects. The material is incredibly durable and will allow heavy machinery to easily pass over.


Riprap (Rip Rap) refers to limestone that is a further step-up in size, typically ranging from 6” to 36” in diameter. These rocks are very large in size and are typically used in erosion control and for stability purposes. Riprap can also be used around culverts, bridges, drains, and other banked slopes that run the risk of washing away in heavy rain or when exposed to heavy waters.

River Rock Materials

Pea Gravel

Pea gravel is made of smaller rocks (<3/8” diameter). The coloring of the material depends on the root source material: limestone is available in varying shades of tan and white while river rock is available in a mixture of tan, red, brown, and other natural colors. Pea gravel is a popular choice for landscaping, playgrounds, walking paths, driveways, patios, gardens, and other areas that are more focused on appearance rather than utility.

Screened River Rock

Screened River Rock refers to a river rock that has been filtered with a series of sieves so that the final product is a consistent size range. These rocks can be various sizes, depending on the quarry, and typically range from 3/8” to 2” in size. Screened river rock can also come washed or unwashed, depending on the quarry capabilities, which refers to if the rock has been cleaned of any natural sediment attached to the rocks when mined. Screened rock, particularly the 1” #57 rock variety, is very popular in construction projects and is a popular additive to concrete. The material is excellent for landscaping purposes, but is not always a great fit for a driveway, walkway, or otherwise project requiring stability. The material’s round edges prevents any type of lock-in and allows the material to wiggle out of the way as pressure is applied.

Oversize River Rock

Oversize River Rock refers to a river rock that is larger than 2” in diameter. Oversize river rock should be produced at any quarry that is capable of mining river rock, but will not always be available in a washed variety. Because of the rocks’ large size, it can be rather tough on washing and screening equipment, meaning that a quarry with specialty equipment capable of handling the rocks larger size. This rock is almost exclusively used for landscaping purposes.

What does Twisted Nail do?

We at Twisted Nail Sand & Gravel provide an easy, efficient way for our customers to have their aggregates sourced and delivered. As experts in both the trucking and aggregate sides of your project, we can provide trucking for the materials that you have sourced or can provide fully landed quotes by sourcing the materials that you need. When it comes to quarries and to material delivery, we offer a combination of pit-to-plant, pit-to-jobsite, and pit-to-consumer hauling; this means that no matter where you need aggregate, Twisted Nail and our team of expert owner operators can deliver. We operate in and around Waco, Austin, and Bryan, Texas. We look forward to hearing back from you and are confident that we are the aggregate solution to ensure your job is on time and on budget!


What is a quarry, and how is it different from a mine?

A quarry is a type of mine called an open pit mine, which is open to the earth’s surface rather than situated below the ground. Quarries, Texas quarries in particular, are used to extract raw materials such as rocks, dirt, and sand that will be repurposed into building materials.

How can quarry direct trucking benefit me as a customer, and what advantages does it offer over other transportation methods?

Quarry direct trucking streamlines the delivery process to bring you the materials you need, where you need them, when you need them. The three options for direct trucking include pit-to-plant, pit-to-job site, and pit-to-consumer.

What types of materials are produced in quarries in Austin and Waco, Texas?

The Austin and Waco quarries boast an impressive range of high-quality aggregate materials. The main materials found are river rock, limestone, granite, and recycled materials. The specific materials are offering in the following popular formats: Flex Base, State Spec Road Base, Screened Rock, #57 Rock, Bull Rock, Rip Rap, Concrete Sand, Washed Sand, Masonry Sand, Manufactured Sand, Select Fill, Common Fill, Top Soil, Pit Run, Recycled Concrete and Asphalt Millings. These aggregates encompass diverse varieties like limestone, river rock, granite, sand, fill dirt, topsoil, recycled concrete, and recycled asphalt, catering to a wide array of construction needs.

How are the materials produced in quarries used in construction and other industries?

Some of the major industries which rely on materials produced in quarries include construction, transportation, and manufacturing. Aggregates such as sand, gravel, and rock are used to build roads, pathways, gardens, and runways, as well as buildings and their foundations. Certain quarries also produce minerals like clay and sand which are used in various manufacturing processes.

What are the environmental and safety concerns associated with quarry operations in Austin and Waco, Texas?

With all the extractions that happen at quarries in Texas, environmental and safety concerns include pollution, erosion, and worker safety. The most common forms of pollution are noise, water, and dust/air pollution, and quarry operations can also erode the soil, which affects local wildlife populations and water quality. Finally, workers may be put at risk because of the heavy machinery and blasting involved, or by being exposed to pollution and hazardous materials which can lead to health problems. However, quarry operators implement various sustainable measures, such as reclamation plans and water conservation, to mitigate their negative environmental impact.