Plastic Core Trays Explained: A Practical Guide for Mining and Exploration Professionals

What Is a Plastic Core Tray?

A plastic core tray (also known as a core box or sample tray) is a specialized storage container designed to hold drilled rock core samples in an organized, secure manner. These trays are typically made of heavy-duty polypropylene or HDPE plastic – often using recycled material – to ensure high strength and durability in harsh field conditions. Each tray has parallel channels or compartments that keep each cylindrical core segment aligned in sequence, with space for labels, so geologists can preserve the exact order and orientation of the core. The key purpose of a core tray is sample storage: protecting the only physical record of what lies beneath the surface and maintaining the integrity of those geological samples from the moment they’re drilled until they reach the laboratory and beyond.

Plastic core trays have largely replaced traditional wooden or metal core boxes in modern exploration projects. Why plastic? Because a quality plastic tray is lightweight, tough, and resistant to the elements, unlike wood which can rot or metal which can rust. Many plastic trays today are molded from recycled plastic, turning waste material into a valuable tool for the field. In essence, a plastic core tray provides a long-lasting, eco-friendly way to store and transport core samples without compromising on strength or performance. It is an unassuming yet essential piece of equipment underpinning geological mining sample storage and exploration data management.

Why Core Storage Matters in Mining and Exploration

Storing drill core samples properly is far more than a housekeeping task – it’s critical to the success of mining and exploration projects. Core samples contain the information needed to discover and evaluate mineral resources, so how they are handled and stored has direct impacts on data quality, safety, and costs. Here’s why core storage matters:

• Preserving Sample Integrity: Rock cores are often fragile or fractured, and if they become broken, mixed up, or contaminated, your geological data can be compromised. Using sturdy core trays keeps samples intact, aligned, and clearly labeled, which ensures accurate geological logging and assay results. A compromised core can distort models and mislead decisions, whereas a well-preserved core provides reliable data for resource estimates and project planning.

• Logistics & Traceability: From remote drill sites to the laboratory, samples may be transported over long distances. Robust core trays that are stackable and secure allow cores to be moved safely without shifting or damage. Their lightweight design also cuts down on freight weight, easing transport from field to core shed or lab. With trays keeping everything organized and documented, critical information isn’t lost in transit, and each piece of core remains traceable to its depth and location.

• Long-Term Storage & Compliance: In many mining jurisdictions, companies are required to archive core samples for years or decades as a reference and for compliance with reporting codes. Plastic core trays excel in long-term storage because they don’t rot or corrode – they maintain their integrity against moisture, pests, and UV exposure over time. This means geological records stay preserved for future study or audits. Proper core storage also helps companies meet regulatory requirements (avoiding regulatory risks of non-compliance) and be ready for re-analysis with new techniques down the line.

• Cost and Efficiency: Poor storage can lead to costly problems. If core samples are lost or ruined, a company might have to re-drill holes at great expense, or face project delays due to missing data. Investing in good core trays is a relatively small cost that protects the huge investment of drilling. It improves onsite workflow (cores can be logged and sampled more efficiently when neatly stored) and safeguards against the nightmare of having to tell investors that critical samples went missing or got mixed up. In short, quality core trays de-risk the exploration process and save money by preventing damage and data loss.

Where Plastic Core Trays Are Used

Plastic core trays are utilized anywhere rock and soil samples need to be preserved, across a range of industries and research fields. Key use cases include:

• Mineral Exploration: In mining exploration drilling (both surface and underground), core trays are standard equipment for storing cores from diamond drilling. Whether it’s a gold, copper, or nickel project, geologists rely on geological core trays to keep hundreds or thousands of meters of drill core organized for logging and sampling. Exploration teams worldwide have adopted plastic core trays as a reliable solution – they are “trusted by core drilling and exploration teams, mining companies, and geologists” on projects of all sizes.

• Geotechnical Investigations: Engineering and geotechnical firms use core trays to store rock cores extracted during site investigations for civil projects (like dam construction, tunnels, or foundations). These cores undergo laboratory tests for strength, porosity, etc., and must be kept intact. Often, geotechnical drilling uses larger core diameters (e.g. HQ size) to retrieve more material for testing, and plastic trays capable of holding those larger cores are commonly used. The durability of plastic is especially valued on long geotech programs where cores might be stored outdoors at field sites for extended periods.

• Oil & Gas Exploration: In oil and gas, when continuous core samples are cut from a well (for instance, coring through a reservoir or an oil sands formation), those core sections are placed in trays or core boxes for examination and storage. Plastic core trays can accommodate the often large-diameter cores from petroleum wells (sometimes PQ or larger). For example, oil sands exploration may yield very wide cores, requiring extra-large trays like the SQ size to hold them. These trays make it possible to safely transport core from the rig to specialized core labs for analysis of porosity, hydrocarbon content, and other reservoir properties.

• Academic and Research Labs: Universities, geological surveys, and research institutions maintain libraries of core samples for study and education. Plastic core trays provide a uniform system to catalog these cores – from teaching collections in geology departments to national core repositories. For instance, the U.S. Geological Survey’s Core Research Center stores large rock core collections in warehouses to preserve them for scientists. Using durable trays or core boxes ensures that even decades-old research samples remain in good condition for geoscientists and students. In short, any setting that involves preserving physical samples of the earth’s crust can benefit from the longevity and convenience of plastic core trays.

Advantages of Plastic vs. Wood or Metal Core Trays

Modern plastic core trays offer significant advantages over the traditional wood and metal core boxes, across multiple factors important to field operations. Below we compare these core tray types and highlight why plastic is now the industry standard:

• Durability & Toughness: Plastic trays are extremely durable in tough field conditions. They won’t warp, rot, or splinter like wood, and they won’t rust or dent like metal. High-quality polypropylene/HDPE trays are engineered to support heavy rock cores without cracking, while also absorbing shocks (e.g. if dropped) without permanent damage. In contrast, wooden boxes can break or decay after repeated exposure to moisture, and steel trays can corrode (especially when cores contain acidic sulfides) and become brittle over time. Plastic’s inherent resistance to water and chemicals means it maintains its structural integrity for years in the field.

• UV and Weather Resistance: A crucial benefit of plastic core trays is their ability to withstand harsh weather and UV radiation. Many plastic trays are UV-stabilized so that prolonged sun exposure won’t cause cracking or degradation. They also handle rain, humidity, and temperature swings without issue – plastic does not swell or lose strength when wet, and it doesn’t become brittle in cold. Metal trays, on the other hand, can get extremely hot under a blazing sun (and dangerously “unsafe to handle” in extreme heat), and they tend to rust if exposed to rain. Wooden trays can dry out and crack in hot climates or grow mold and rot in humid conditions. By using plastic trays, exploration teams can confidently store core outdoors or in core yards, knowing the trays will hold up through intense sun, storms, or freeze-thaw cycles.

• Lightweight for Easy Handling: Plastic core trays are much lighter than their metal or wood counterparts, making them far easier and safer for workers to carry. An empty plastic tray typically weighs only a few kilograms, whereas a steel core box of comparable size can weigh many times more – a filled steel tray can reach 20–25+ kg, which is very cumbersome to lift and transport. The lighter weight of plastic reduces strain on geologists and field technicians when moving trays around drill sites or core storage facilities. It also means lower shipping and transport costs: for example, one case study noted that switching from steel to plastic trays significantly cut down on helicopter fuel usage when flying cores from remote drills, thanks to the weight savings. In short, plastic trays improve both ergonomics and logistics by trimming dead weight without sacrificing strength.

• Stackability & Stability: Plastic trays are purpose-built to be stacked safely, which is vital for efficient core storage and transport. Most designs have interlocking features or ribbed bases that allow trays to nest securely without sliding. This stability means you can stack many loaded trays on pallets or in trucks without them toppling over – an important advantage over warped wooden boxes or smooth metal trays that might slip. Plastic’s combination of light weight and strength also lets you build taller stacks; large stacks of metal trays are often impractical due to their weight and risk of collapse. Additionally, plastic tray dimensions are usually standardized to optimize pallet space (fitting neatly into typical shipping container or warehouse rack sizes) so you get more core per pallet and maximize storage efficiency. This stackability saves space and simplifies both field handling and long-term warehousing of core samples.

• Sustainability: Unlike single-use or short-lifespan wood boxes, plastic core trays can be reused for many years, and increasingly they are made from recycled plastic, further reducing their environmental footprint. Every recycled plastic tray represents a chunk of waste diverted from landfill and a reduction in the need for new plastic production. While metal trays are also reusable, they require energy-intensive processes (mining and smelting metals) to produce and are heavy to ship (increasing fuel emissions). Wood trays come from a renewable resource, but using them in large quantities can contribute to deforestation if not sourced sustainably, and treated wood can release chemicals at end-of-life. In terms of longevity, plastic trays outlast wood by multiple projects, meaning fewer replacements and less waste over time. Overall, choosing plastic – especially recycled plastic – core trays supports sustainability goals by combining long service life with the possibility of recycling the tray itself when it’s eventually worn out. This makes plastic trays the environmentally and ESG-friendly choice among core tray types.

Different Sizes and Standards Explained (BQ, NQ, HQ, PQ, SQ)

Drilled core comes in various diameters, so core trays are manufactured in different sizes to match. In the mining and geotechnical industry, the most common sizing system is defined by the Diamond Core Drilling Manufacturers Association (DCDMA) wireline standards, which use letter codes BQ, NQ, HQ, PQ (and less commonly SQ) to denote core diameters. Each standard size has corresponding tray dimensions to securely hold that core. Here’s a breakdown of the typical core box sizes and what they mean:

• BQ – ~36 mm core diameter: BQ is the smallest standard wireline core size. These cores are relatively narrow, so BQ plastic core trays can hold more meters of sample per tray – usually about 6–7 meters of core per tray, divided into several channels. BQ is often used in early-stage exploration or where drill equipment needs to be very light (e.g. helicopter-supported drilling in remote areas or very hard rock drilling). The smaller core and tray size trade some sample volume for easier handling and transport in difficult terrain.

• NQ – ~47 mm core diameter: NQ is the most widely used core size in mineral exploration. It strikes a balance between obtaining enough sample for analysis and keeping drilling efficient. A standard NQ plastic tray holds around 5–6 meters of core, typically split into 5 one-meter rows. NQ trays are ubiquitous in gold and base metal exploration – this size provides sufficient rock for geologists to examine mineralization and perform assays, while still being reasonably compact and fast to drill. For many projects, NQ is the “default” core size and tray choice unless there is a specific reason to go bigger or smaller.

• HQ – ~63.5 mm core diameter: HQ is a larger core size chosen when more sample is needed or to improve recovery in fractured ground. An HQ core tray usually carries about 4–5 meters of core (the cores are thicker, so fewer fit per tray). HQ is common in geotechnical investigations, where larger core provides extra material for rock strength tests, hydrological sampling, or geological structure analysis. Many mining projects also use HQ in certain situations – for example, when drilling through a complex orebody where a bigger core helps capture structures or coarse gold. The trays for HQ are accordingly wider to fit the ~63 mm cores, and they tend to be a bit heavier when full, but still benefit from plastic’s lighter weight compared to metal.

• PQ – ~85 mm core diameter: PQ is an extra-large core size typically used in specialized scenarios. A PQ tray holds roughly 3–4 meters of core per tray due to the core’s substantial thickness. This size is often seen in the later stages of a project or for specific purposes: for instance, bulk sampling in diamond exploration (larger core means you might actually capture a gemstone or more indicator minerals), or obtaining maximum sample for metallurgical testing in a mining project. PQ cores are heavy and drilling is slower and more expensive, so they’re not used routinely unless needed. Plastic PQ trays are built to handle the weight of these cores while still offering the benefits of durability and stackability for such heavy samples.

• SQ – ~100 mm core diameter (oversize): “SQ” is not an official DCDMA size but a term used for ultra-large cores (often in the range of 96–HQ85 mm or larger). These are relatively rare, but when they are used, it’s often in oil sands or certain geotechnical coring programs that require an exceptionally large core sample. An SQ core tray is essentially a specialty tray for these oversized cores – typically accommodating a similar length per tray as PQ (around 3 meters) because the cores are so large in diameter. Such trays need to be very robust and are usually less common in inventory, but they exemplify the range of sizes available. If your project uses a non-standard or unusually large core, tray manufacturers often list the exact core diameter their trays can fit (sometimes under a metric designation). Always check that the tray’s channel width and depth are sufficient for your core diameter to ensure a snug fit without jamming or rattling.

Each of these tray sizes is engineered to correspond with the drill core produced by certain equipment. The BQ–PQ series is globally recognized, so if you request an NQ tray from a supplier, it will typically be compatible with any NQ core from any drill. Many plastic tray suppliers also design their trays to fit multiple standards (for example, an HQ tray might also fit a similar metric core size used in Europe). When selecting trays, use the core diameter as your guide: match the tray size to the core size to keep your samples secure.

The Role of Sustainability in Core Trays

In an era where mining and exploration companies are increasingly evaluated on their environmental and social performance, even something as humble as a core tray can play a part in meeting sustainability goals. Plastic core trays have evolved to support sustainable practices in a few important ways:

Recycled Materials and Circular Economy: One of the biggest sustainability advantages is that many plastic core trays are now made from recycled plastic. Instead of using all new (virgin) plastic, manufacturers like PCT collect post-consumer plastic waste – such as used packaging – and reprocess it into high-grade polymer suitable for core trays. Advanced recycling techniques ensure these trays have the same strength and performance as those made from new plastic. This approach effectively turns plastic waste into a valuable resource for the mining industry. It embodies a circular economy model: plastic waste is collected and transformed into core trays, and when those trays eventually reach end-of-life years later, the material can be recycled yet again into new products. By choosing trays with recycled content, mining and exploration projects actively reduce landfill waste and lower the demand for fossil-fuel-derived materials.

Solar-Powered Manufacturing: Sustainability isn’t only about what materials you use, but also how products are made. Some leading core tray manufacturers operate solar-powered production facilities, meaning the energy used to mold and fabricate the plastic trays comes from renewable sources rather than fossil fuels. For example, a factory running on a 7.3 MW solar plant can power the entire core tray production line with clean energy, avoiding thousands of tons of CO₂ emissions. In fact, using solar electricity can result in up to a 40% reduction in carbon emissions per tray produced compared to conventional manufacturing. By cutting the carbon footprint of each tray during production, these companies help mining customers lower the indirect (Scope 3) emissions associated with their supply chain. The result is not just a more sustainable product, but a cleaner manufacturing process that aligns with global efforts to minimize industrial greenhouse gas emissions.

Alignment with ESG Goals: For mining companies under pressure to improve their Environmental, Social, and Governance (ESG) performance, switching to environmentally friendly core trays is a small but meaningful step. It demonstrates a commitment to innovation and waste reduction. Using recycled plastic trays in the field shows stakeholders that the company is proactively reducing plastic waste and supporting recycling markets. Additionally, the long service life of rugged plastic trays means fewer replacements are needed, which minimizes ongoing waste and resource consumption. All these factors contribute to a lower environmental impact over the lifetime of an exploration project. In an industry often associated with heavy resource use, adopting recycled, solar-produced core trays is a tangible way to embed sustainability into daily operations. It’s a win-win solution: the project benefits from the trays’ durability and efficiency, while also advancing its sustainability agenda and reducing its environmental footprint. In summary, the modern plastic core tray isn’t just about storing rocks – it’s part of a broader push toward greener exploration practices.

How to Choose the Right Tray for Your Project

Selecting the appropriate core trays for your needs will ensure you get the most out of this important tool. Different projects have different requirements, so consider the following factors when choosing the best core tray for your situation:

• Project Type and Scope: First, align your tray choice with the type of project and its scale. Are you drilling deep mineral exploration holes, doing shallow geotechnical borings, or collecting core for an oil & gas program? For a mining exploration project, NQ-sized plastic trays are a common all-purpose choice, as many such programs default to NQ core diameter. Meanwhile, geotechnical projects often benefit from larger trays (HQ or PQ) because they typically drill bigger cores to analyze rock properties. An infrastructure project might need HQ trays to hold core for engineering tests, whereas a grassroots exploration might start with BQ or NQ to minimize costs. Consider also the volume of core: a long-term, large drilling campaign will warrant investing in a robust set of trays (possibly even “premium” reinforced models) that can be reused across many holes. In contrast, a short, one-off drill program in an area with easy resupply might get by with a simpler or smaller number of trays. Always ensure the trays you choose are proven in your industry – e.g. trays marketed for “geology and mineral exploration” will be suited for field conditions, whereas a makeshift solution not designed for core could fail at the worst time.

• Climate and Environment: Match the tray material and design to the climate in which you’ll be working. In very hot, sunny climates, UV-resistant plastic trays are typically the best core tray option because they won’t degrade or become dangerous to touch in extreme heat. Metal trays under tropical sun can become searing hot (and even burn handlers), and they may rust quickly in high humidity or monsoon conditions. Wooden boxes in rainy or jungle environments often warp, rot, or get infested by insects, risking your samples. Conversely, in freezing climates, plastic trays hold up well – they don’t turn brittle in the cold, whereas some plastics or poorly treated wood might crack. If your project involves storing core outdoors (common in remote exploration camps), choose trays that have drainage holes and UV stabilizers, and avoid materials that can absorb water. In short, for harsh environments (deserts, high-altitude mountains, Arctic tundra, tropical rainforest), rugged plastic trays are proven to withstand the elements and keep cores safe where other materials would fail.

• Sample Size (Core Diameter): The tray must fit the core! Always select trays that are designed for the core diameter your drilling method produces. If you’re drilling NQ-size diamond core, get NQ trays; for HQ core, use HQ trays, and so on. The industry standards (BQ, NQ, HQ, PQ, etc.) make this straightforward – reputable tray suppliers will label which standard their trays are compatible with. Using the correct size prevents the cores from rattling around (too loose) or not fitting at all. For example, wireline drilling with an HQ core barrel will require an HQ tray that has the right compartment width and depth to hold ~63 mm cores securely. Similarly, if your program plans to transition from, say, NQ to HQ in deeper holes, you might need both NQ and HQ trays available. In general, err on the side of slightly larger tray if you’re unsure, but avoid oversized trays for small cores as they might allow movement. Also, consider the length of core per tray – most trays are about 1 meter long and hold a certain number of core rows (as discussed in the size guide above). Ensure you have enough trays ordered to handle the total meters of core expected, keeping in mind how many meters each tray can hold.

• Transportation and Handling: How will the core trays be moved around during and after drilling? This can influence what tray features are most important. If your project is in a remote location with limited access, portability is key. Lightweight plastic trays can be carried by hand or flown via helicopter sling loads much more easily than heavy steel trays, which has saved companies significant money in transport costs. Look for trays with ergonomic touches like molded handles or comfortable grips if manual carrying is anticipated – hauling core in and out of a drill site is tough work, so every convenience helps. Also plan for how trays will be shipped or stored: if you need to truck them long distances or overseas, make sure the trays have consistent dimensions that palletize efficiently. Most plastic core trays stack neatly, which is ideal for maximizing cargo space and keeping things organized during transit. If shipping weight is a concern (e.g. air freight or many truckloads), plastic’s weight advantage will reduce fuel use and cost. On site, consider investing in tray stands or racks if you’ll be logging core extensively – the trays should fit whatever racks or shelving you use. And if core will be frequently moved (from rig to camp to lab), robust stackable trays with locking lugs will ensure tall stacks don’t tip over en route. In summary, choose core trays that make the logistics as smooth as possible for your specific project.

• Budget and Sustainability Priorities: While plastic trays might have a higher upfront unit cost than basic wood boxes, they typically offer far better long-term value. If your budget accounts for the entire project lifecycle, the trays that last longer and protect core better will save money by avoiding damage, replacements, and accidents. However, if you are on a shoestring budget for a very short project, some trade-offs might be considered (for example, using a few wooden core boxes if conditions are dry and disposal is not an issue). That said, many companies are now factoring sustainability into their procurement. If your company has ESG commitments or simply wants to reduce its environmental impact, choosing recycled plastic core trays is a smart move. They check the boxes for performance while also demonstrating that you’re using recycled materials and supporting a circular economy. Showing that you’ve opted for solar-manufactured, recycled trays can even be a talking point in sustainability reports. Ultimately, the “right” tray is one that meets your technical needs and aligns with your project values. In mining and exploration today, plastic core trays (especially recycled ones) often provide the best balance of durability, ease of use, and environmental responsibility, making them the go-to choice for serious professionals.

Finally, remember that core trays are an investment in your data quality. The trays you choose will directly affect how well your irreplaceable core samples are preserved. By considering the factors above – project type, climate, sample size, logistics, and sustainability – you can confidently select the optimal plastic core tray for your drilling program. With the right trays in hand, you’ll ensure your cores are stored safely from the drill site to the core farm to the laboratory, all while improving efficiency and supporting the broader goals of your project.