Aquamarine, a captivating gemstone known for its striking blue to greenish-blue color, is a variety of the mineral beryl. Its name originates from the Latin phrase meaning “water of the sea,” a reference to its oceanic hue. Searching for this crystal, which is composed of beryllium aluminum silicate, offers a rewarding challenge for the dedicated rockhound. Finding aquamarine requires a combination of geological knowledge, the right equipment, and careful field identification skills.
Understanding Aquamarine’s Geological Home
Aquamarine formation is tied to the crystallization of granitic magmas, specifically occurring within a rock structure known as a pegmatite. Pegmatites are a type of igneous rock characterized by extremely coarse grain sizes, which allows large crystals to develop over time. These formations represent the final, volatile fluid phase of cooling magma, where rare elements like beryllium are concentrated. The presence of trace amounts of iron within the crystal structure of the beryl is what provides the characteristic blue coloration of aquamarine.
The crystals typically grow in open spaces, called pockets or vugs, within the pegmatite mass or along its margins. Aquamarine is often found alongside common pegmatite minerals such as quartz, mica, and feldspar. Globally, the most significant deposits are concentrated in Minas Gerais, Brazil, and the mountainous regions of Pakistan. Within the United States, notable localities include Mount Antero in Colorado and the coastal pegmatites of Maine. Searching in areas known for these coarse-grained igneous intrusions increases the probability of discovery.
Essential Tools and Preparation for the Search
A successful rockhounding trip begins with preparation, focusing on both legal access and necessary equipment. Before venturing out, it is important to confirm property boundaries and understand local regulations. Collection for personal, non-commercial use is often permitted in reasonable quantities on public lands, but private land always requires explicit permission from the owner. Wearing sturdy hiking boots for uneven terrain and carrying sufficient water and a first aid kit is important.
The primary tool for the search is a durable rock hammer, preferably one with a pointed pick end for splitting and prying. A set of masonry chisels is necessary for working on the host rock, and a pry bar can assist in moving larger pieces of matrix. Eye protection is mandatory when striking rock with a hammer or chisel to protect against flying fragments. For examining potential finds, a 10x magnification jeweler’s loupe is a helpful tool for closely inspecting crystal faces and inclusions.
Key Characteristics for Field Identification
Recognizing aquamarine in the field depends on observing its physical and crystallographic properties. The color ranges from a pale blue to a more saturated blue-green, a hue caused by ferrous iron within the beryl mineral structure. Aquamarine crystals typically form as hexagonal prisms, appearing as columns with six sides. They can be found embedded in the rock or sometimes loose within a clay-filled pocket.
The mineral exhibits a high degree of transparency and a vitreous or glassy luster on its crystal faces. Its hardness, rating between 7.5 and 8 on the Mohs scale, helps distinguish it from softer minerals. When checking for a potential find, look for the characteristic columnar shape and test the durability by attempting to scratch it with a steel tool. While quartz is also a hard, clear mineral, it lacks the distinct hexagonal column structure and specific blue hue of aquamarine.
Safe Removal and Handling
Once an aquamarine crystal is located within the pegmatite matrix, extraction must be approached with precision to avoid damage. Aquamarine, while hard, can be brittle, and excessive force may cause it to cleave or fracture. The strategy involves carefully removing the surrounding host rock rather than directly striking the crystal itself. Using chisels and a small crack hammer, work slowly around the crystal, employing gentle pressure to separate the specimen along natural fractures.
If the crystal is found within a clay or soil-filled pocket, use a small, non-metallic tool like a wooden pick to gently clear the material away. Wrap each crystal individually in a soft material, such as cotton or newspaper, before placing it in a collection bag for transport. Initial cleaning can be accomplished using warm water and a mild dish soap to remove surface dirt and clay.