American Museum of Natural History, or AMNH, as it is commonly called, is located on the Upper West Side of New York City. It is considered one of the world’s preeminent educational, cultural and scientific institutions. This huge complex has over 25 interconnected buildings that house over 40 permanent exhibition halls, a planetarium, and a library.

Only about 3% of its millions of specimens and cultural artifacts are on display. Still, one needs many visits to fully explore all of its exhibited plant, animal, fossil, mineral, rock, meteorite, human remains etc.  Exhibits go into great detail to educate visitors about the things they are seeing, how they came about, and past/current threats to their environments. It is truly an amazing museum.

While fascinating to explore, we also find ourselves often getting turned around or scratching our heads on how to get to the areas we want to explore. Fortunately, the staff is good at pointing the way. And the museum has a free app that you can use on your cell phone to help you find your way.

Minerals and Gemstones

In 2021, we visited ANMH primarily for its exhibition on minerals and gems. The obvious draw of the exhibit is the specimens themselves, from giant, shimmering geodes to small, meticulously cut diamonds and virtually every type of mineral and gemstone in between.

One can appreciate the exhibit in any number of ways such as in the context of:

• The diversity of minerals (more than 5,500 unique species);
• Their ages (up to more than a billion years);
• Their recurring crystalline patterns, sizes (such as that of the 12-foot tall geode to a 14,500-pound garnet and 600-pound topaz); and
• The huge range of beautiful colors (and in some cases, iridescence).

You can appreciate the minerals for their practical uses such as the roles of:

• Feldspar in producing ceramic glazes and in the manufacturing of glass, plastic, rubber and paint;
• Rare earth minerals in producing virtually all of the electronic products that we have come to depend on;
• Garnets as abrasives;
• Filtering the water we drink;
• Ore minerals in smelting and creating useful metals;
• Clays (which consist of minerals that have been weathered and otherwise eroded into dust and then compressed) in producing ceramics, plastics, and paper; and
• Salt as a foundation for human life as in hydrating cells and in transmitting signals among neurons.

Or you can just appreciate the beauty and the elegance of any of the wide range of precious and semi-precious gemstones, including both inorganic and organic (pearls, coral, amber, etc.), both in their natural states and after they have been cut and/or polished.

A College Course in Geology

The exhibit goes far beyond the utility, beauty, size and age of minerals. As a New York Times review portrayed it, it is almost a college course in geology.

The begins with a discussion of the origin of the first elemental minerals in the cores of stars. It then moves on to how others were formed in conjunction with solar systems and planets. Existing minerals continue to evolve and new ones continue to be created often through some combination of heat, pressure, and water. Examples include volcanic eruptions; tectonic pressures; thermal vents;  or even minerals being dissolved in and precipitated out of water.

It then goes into depth (sometimes too much depth for us) in discussing the chemical compositions and rationale for the different types of mineral classifications (both chemical and structural). It discusses the differences among and the hierarchy of:

• Crystals, which are solid substances with naturally occurring 3D geometric forms with symmetrically arranged plane faces
• Minerals, which are naturally occurring inorganic substances with crystalline structures; and
• Rocks, which are amalgams of solid mineral materials.

In summary rocks are minerals and minerals have crystalline structures.

And it explains how different minerals have different combinations of properties such as:

• Physical, such as their hardness and cleavage;
• Chemical, such as their solubility in water and other liquids and melting point;
• Electrical, such as whether and to what extent the conduct or insulate electricity;
• Magnetic, whether or not they are naturally polarized or, in some cases can become polarized in certain situations; and
• Optical, such as their color, clarity, and luster.

Mineral Optical Properties

A section of the exhibit focused on the optical properties of minerals. Color is determined by how different materials absorb, reflect, and refract wavelengths of visible light. Different parts of the same mineral can appear as different colors. Some minerals also absorb and reflect ultraviolet light and thereby appear iridescent, either as florescent or luminescent. What’s interesting is that rocks that appear as a bland grayish-brown under normal light take on vivid colors in ultraviolet light. Inclusions in a mineral can result in cats’ eye-like patterns. Gem cutters can split wavelengths in various ways to create sparkle and the perception of different colors.

Overall, the exhibit was a fascinating, if somewhat dense and pedantic examination of the nature of minerals.

The Big Bang and its Aftermath

We also explored an exhibit that explained the birth and increasingly expanding universe, beginning with the Big Bang (13.5 billion years ago), how galaxies began to form from clouds of gas and dust (roughly 9 billion years ago), how the stars began producing and expelling the basic elements (beginning with hydrogen, oxygen, carbon and iron) which began coalescing into solar systems about 5 billion years ago and the first earth rocks (about 4 billion years ago).

Since the earth’s surface, at that time, was being continuously bombarded with asteroids and comets, it was far too hot for liquid water to form or for life to begin to take hold. This began to change about 3.5 billion years ago when the bombardment slowed and the earth cooled, water form and the first single-cell bacteria began to emerge (as evidenced by fossils).

• Bacteria began sunlight to photosynthesize food from water and carbon dioxide (which produced oxygen).
• By 2 billion years ago, an oxygen-rich atmosphere began to emerge.
• This led to the creation of multi-cell algae (about 1.2 billion years ago) and the first animals (trilobites) with eyes about 1 billion years ago.
• From there came dinosaurs (240 million years ago), the great extinction (65 million), and the emergence of mammals.
• Humans first came on the scene only about 35,000 years ago.

One of the big outstanding questions is how the moon was created. Hypotheses include it being:

• Co-creation with the earth;
• A part of the earth was spun out into space and fell into orbit; or
• A mass from elsewhere in the solar system that was pulled into orbit by the earth’s gravity.

In any case, much more is known about the moon after it went into earth orbit. For example, while the earth continued to evolve through volcanic and tectonic activity, the moon stopped evolving about 2 billion years ago, when lava stopped flowing.

Much is also known about the synergy between the earth and the moon. This includes:

• The moon’s effect on the orientation and spin of the earth;
• How the moon pulls the tides and how this slows the rotation of the earth (which causes days to get longer (by about 16 seconds every million years); and
• How the moon is adapting to this change by moving further away from the earth (about 3.8 centimeters per year to maintain the same rate of rotation around its axis in a way that keeps the same side o the moon always facing the earth.

If these explanations are a bit beyond the realm of comprehension, the story of the moon is, so to speak, brought down to earth by an incredible series of photographs that NASA took of its moon missions. Everything from photos of the asteroid-scarred surface and remnants of its last lava flows to pictures of the earth rising over the moon’s horizon and close-up pictures of astronaut spacewalks and moon walks.

Continuing Evolution of the Earth

Another exhibit examines the recent and current state and the future of the earth, including:

• How the earth’s crust floats on a layer of magma that lies a mere 8- to 120 km below the surface;
• How the current continents and mountains formed and continue to change by the process of continental drift;
• How this drift, especially at the intersections where different plates meet, create volcanic hot spots and ongoing pressures that create earthquakes (and, going back to the minerals exhibit, create and transform minerals/rocks).
• The volcanism of the west coast’s Cascade Mountains, the continual pressure and slippage along the San Andreas fault (300 km over the last 30 million years), and the consequences of a major quake, such as Alaska’s 9.6 quake in 2006.

The exhibit then discusses the continual changes in the earth’s climate and how natural causes cannot explain the current rate of change that has:

• Melted polar ice caps;
• Increased global temperatures by 0.4 degrees Centigrade from 1900 to 2000
• Increased sea levels by 8.2 cm from 1880 to 2009;
• Increased the risk of extreme weather events (Europe had extreme weather once every 50 years in the early 1990s. Today it is 1 every 5 years); and
• Increased the amount of CO2 in the atmosphere by two billion tons since the beginning of the Industrial revolution.

It demonstrated this linkage with exhibited Greenland ice cores (representing 100,000 years of history) and earth core samples (representing 3.6 million years of history).

Inside You: Microbiomes

When we were last there in 2017, we explored another interesting exhibit that explored the many critical roles that bacteria plays in the human body. It gave a brief overview of the thousands of types of bacteria on the skin and in the mouth and then focused on the incredible variety and volume (about 100 million microbes per milliliter) in the gut. This bacteria (which makes up the so-called microbiome or community of micro-organisms that live together) is found through the entire gastric system.

Although each person’s microbiome is different, there are commonalities among people who live in the same geographies, have similar diets, and are exposed to similar environmental mental conditions. Microbiomes play critical roles in helping humans digest food and fight disease. They are also believed to play important, but much less well-understood roles in a number of other functions such as appetite (by “telling” the brain when to find food), moods, and sleep patterns (the microbiome directly produces 20 percent of the body’s serotonin). They are also thought to play a contributory role in weight gain and loss, mental health, and even autism.

In fact, experiments in transferring part of one individual’s microbiome to another is already beginning to suggest a new way to control a person’s food intake and ways to treat depression. Although little is truly known of the role of the microbiome, much less in how to use it to improve an individual’s physical and mental health, it shows enormous potential.

The Opulent Ocean

This exhibit is an adjunct to the museum’s Hall of Ocean Life. It provides reproductions of 46 rare illustrations that portray the first truly scientific efforts to understand the oceans some 400 years ago. These sketches portray the mystery and sheer beauty of dozens of amazing species and provide clues as to their anatomy, habits, and evolutionary origins. The large Ocean Life exhibit, meanwhile, provides an overview of thousands of species of vertebrates and invertebrates that populate different sections of the ocean, from near-shore estuaries and shallow coral reefs to the open ocean and deepest trenches, the interaction among these species and the impact of climate and climate change on all of them.