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Why are rubies red and emeralds green? Their colors come from the same metal in their atomic structure

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theconversation.com – Daniel Freedman, Dean of the College of Science, Technology, Engineering, Mathematics & Management, University of Wisconsin-Stout – 2025-02-04 07:42:00

Why are rubies red and emeralds green? Their colors come from the same metal in their atomic structure

Rubies get their bright color from some fascinating chemistry.
Matthew Hill/Bloomberg Creative Photos via Getty Images

Daniel Freedman, University of Wisconsin-Stout

The colors of rubies and emeralds are so striking that they define shades of red and green – ruby red and emerald green. But have you ever wondered how they get those colors?

I am an inorganic chemist. Researchers in my field work to understand the chemistry of all the elements that make up the periodic table. Many inorganic chemists focus on the transition metals – the elements in the middle of the periodic table. The transition metals include most of the metals you are familiar with, like iron (Fe) and gold (Au).

One feature of compounds made with transition metals is their intense color. There are many examples in nature, including gemstones and paint pigments. Even the color of blood comes from the protein hemoglobin, which contains iron.

Investigating the colors of compounds containing transition metals leads you into some really amazing science – that’s part of what drew me to study this field.

Rubies and emeralds are great examples of how a small amount of a transition metal – in this case, chromium – can create a beautiful color in what would otherwise be a fairly boring-looking mineral.

Minerals and crystals

A small, round ruby
Rubies appear red because they absorb blue and green light.
benedek/E+ via Getty Images

Both rubies and emeralds are minerals, which is a type of rock with a consistent chemical composition and a highly ordered structure at the atomic level.

When this highly ordered structure extends in all three dimensions, the mineral becomes a crystal.

With a theory developed by physicists in the 1920s called crystal field theory, scientists can explain why rubies and emeralds have the colors they do. Crystal field theory makes predictions about how a transition metal ion’s structure is affected by the other atoms surrounding it.

Rubies are mainly made up of the mineral corundum, which is composed of the elements aluminum and oxygen in a regular, repeating array. Each aluminum ion is surrounded by six oxygen ions.

A chemical structure diagram showing
A crystal of corundum looks like this at the atomic level, with the aluminum ions shown as red balls and the oxygen ions shown as white balls. Each aluminum ion is surrounded by six oxygen ions, and each oxygen by four aluminums.
Eigenes Werk/Wikimedia Commons, CC BY-SA

Emeralds are mainly made up of the mineral beryl, which is made from the elements beryllium, aluminum, silicon and oxygen. Beryl’s crystal structure is more complicated than corundum’s because of the additional elements in the formula, but each aluminum ion is again surrounded by six oxygen ions.

A rectangular emerald
Emeralds appear green because they absorb red and blue light.
SunChan/E+ via Getty Images

Pure corundum and beryl are colorless. The brilliant colors of rubies and emeralds come from the presence of very small amounts of chromium. The chromium replaces about 1% of the aluminum in the corundum or beryl crystal when a ruby or emerald forms underground at a high temperature and pressure.

But how can one element – chromium – create the red color of a ruby and green color of an emerald?

Color science

Rubies and emeralds have the colors they do because, like many substances, they absorb some colors of light. Most visible light, like sunlight, is composed of all the colors of the rainbow: red, orange, yellow, green, blue, indigo and violet. These colors make up the visible light spectrum, which is easy to remember as ROY G BIV.

A diagram showing the visible light spectrum, with indigo and violet having shorter wavelengths than red and orange.
Objects absorb some visible light wavelengths and reflect others, which is why we see them as having a color.
Fulvio314/Wikimedia Commons, CC BY-SA

One of the main reasons why objects have a color is because they absorb one or more of these visible colors of light. If a substance absorbs, for instance, red light, it means that the red light gets trapped in the substance and the other colors reflect back to your eyes. The color you see is the sum of the remaining light, which will be in the green-to-blue range. If a substance absorbs blue, it will look red or orange to you.

Unlike the colorless aluminum ion, the chromium ion absorbs blue and green light when surrounded by the oxygen ions. The red light is reflected back, so that’s what you see in rubies.

In an emerald, even though the chromium is surrounded by six oxygen ions, there is a weaker interaction between the chromium and the surrounding oxygen ions. That’s due to the presence of silicon and beryllium in the beryl crystal. They cause the emerald to absorb blue and red light, leaving the green for you to see.

The ability to tune the properties of transition metals like chromium through changing what is surrounding it is a core strategy in my field of inorganic chemistry. Doing so can help scientists understand the basic science of metal-containing compounds and the design of chemical compounds for specific purposes.

You can take delight in the amazing colors of the gemstones, but through chemistry, you can also see how nature creates those colors using an endless variety of complex structures made with the elements in the periodic table.The Conversation

Daniel Freedman, Dean of the College of Science, Technology, Engineering, Mathematics & Management, University of Wisconsin-Stout

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Even as polarization surges, Americans believe they live in a compassionate country

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theconversation.com – Tara Sonenshine, Edward R. Murrow Professor of Practice in Public Diplomacy, Tufts University – 2025-02-11 12:06:00

Even as polarization surges, Americans believe they live in a compassionate country

Most Americans responding to a survey said compassion is declining but still strong.
stellalevi/DigitalVision Vectors via Getty Images

Tara Sonenshine, Tufts University

Compassion comes easily to me.

As the granddaughter of immigrants from Lithuania and Poland who spoke little English, I understand what it’s like to be treated as a stranger in America.

As a journalist, I covered stories of war and trauma in the 1990s, including the crushing of Chinese protests in Tiananmen Square and the fall of the Berlin Wall in 1989, followed by the Soviet Union’s collapse two years later. I covered the war between Iraq and Iran. I witnessed ethnic strife in South Africa and the toll poverty takes in Mexico.

As a professor of cultural engagement and public diplomacy, I have watched and studied how compassion can help build and strengthen civil society.

And having worked in senior levels of the U.S. government for Presidents Bill Clinton and Barack Obama on international conflict resolution, I have learned that compassion is a key ingredient of peacemaking.

Especially now, as President Donald Trump seeks to deport millions of immigrants living in the U.S. without authorization and to stop funding the U.S. Agency for International Development, which has long spent billions of dollars a year helping the world’s poorest people, compassion seems lacking among U.S. leaders.

Perhaps that all explains my curiosity about a new study on the state of compassion in America – part of the glue that holds communities together.

Defining compassion

Sociologists define compassion as the human regard for the suffering of others, and the notion of using action to alleviate this pain.

The report that caught my eye was issued in January 2025 by the Muhammad Ali Center, which the late boxer co-founded 20 years ago in Louisville, Kentucky, to advance social justice.

As the Ali Center explains, compassion starts with the individual – self-care and personal wellness. It then radiates out to the wider community in the form of action and engagement.

You can see compassion at work in the actions of a Pasadena, California, girl, who started a donation hub for teens affected by fires that ripped through the Los Angeles region in early 2025. She began collecting sports bras, hair ties and fashionable sweaters – helping hundreds of her peers begin to recover from their losses in material and emotional ways.

It’s also visible in the estimated 6.8 million people in the U.S. who donate blood each year, according to the American Red Cross.

Resilience in America

While Ali is best known for his battles in the ring and his outspoken political views, he also helped those in need in the U.S. and other countries through large charitable donations and his participation in United Nations missions to countries like Afghanistan, where he helped deliver millions of meals to hungry people.

The researchers who worked on the Ali Center report interviewed more than 5,000 U.S. adults living in 12 cities in 2024 in order to learn more about the prevalence of compassionate behaviors such as charitable giving, volunteering and assisting others in their recovery from disasters.

They found that the desire to help others still animates many Americans despite the nation’s current polarization and divisive politics.

The center has created an index it calls the “net compassion score.” It approximates the degree to which Americans give their time and money to programs and activities that nurture and strengthen their communities.

Cities with high compassion scores have more community engagement and civic participation than those with low scores. A higher-scoring community performs better when it comes to things like public housing and mental health resources, for example. Its residents report more career opportunities, better communications between local government and citizens, more community programs and more optimism around economic development where they live.

The report provides some clues as to what drives compassionate behavior in a city: a sense of spirituality, good education, decent health care, resources for activities like sports, and opportunities to engage in local politics.

All told, Americans rate their country as a 9 on a scale that runs from minus 100 to 100.

The report also identified some troubling obstacles that stand in the way of what it calls “self-compassion” – meaning how volunteers and donors treat their own mental and physical health. Frequent struggles with self-care can lead to rising levels of isolation and loneliness.

Three people pose for a picture in front of an Ali Center backdrop
Jeni Stepanek, left, chair of the Muhammad Ali Index; Lonnie Ali, co-founder and vice chair of the Muhammad Ali Center; and DeVone Holt, the center’s president and CEO, at the launch of the Muhammad Ali Index on Jan. 16, 2025.
Bryan Bedder/Getty Images for Muhammad Ali Center

Doubting their own capacity

The 2025 Compassion Report’s findings show that many Americans still want to live in a compassionate country but also that Americans view the country as less compassionate today than four years ago.

The report delves into gaps in compassion. About one-third of those interviewed acknowledged that there are groups toward whom they feel less compassionate toward, such as people who have been convicted of crimes, immigrants living in the U.S. without authorization and the rich.

Only 29% said they feel compassion toward everyone.

The report also identifies gender gaps. Despite expressing greater awareness of systemic challenges, the women surveyed reported less self-compassion than men.

It’s not the first compassion study ever done. But I believe that this one is unique due to its focus on specific cities, and how it assessed limits on the compassion some people feel toward certain groups.

Helping health and humanity

The Compassion Institute, another nonprofit, seeks to weave compassion training into health care education to “create a more caring and humanitarian world.” It cites the benefits of compassion for human beings, with everything from reducing stress to alleviating the effects of disease on the mind and body.

Academic institutions, including Stanford University, have conducted many studies on how teaching compassion can guide health care professionals to both treat patients better and achieve better outcomes.

A team of Emory University researchers examined how training people to express more compassion can reduce stress hormones levels, triggering positive brain responses that improve immune responses.

Offering an advantage

Although there are plenty of adorable videos of dogs and cats behaving kindly with each other or their human companions, historically compassion has differentiated humans from animals.

Human beings possess powers of emotional reasoning that give us an edge.

Scholars are still working to discover how much of human compassion is rooted in emotional reasoning. Another factor they’ve identified is the aftermath of trauma. Studies have found evidence that it can increase empathy later on.

You might imagine that in a world of hurt, there’s a deficit of compassion for others. But the Ali Center’s report keeps alive the notion that Americans remain compassionate people who want to help others.

My experiences around the world and within the U.S. have taught me that human beings both have the power to be violent and destructive. But despite it all, there is, within all of us, the innate ability and desire to be compassionate. That is a net positive for our country.The Conversation

Tara Sonenshine, Edward R. Murrow Professor of Practice in Public Diplomacy, Tufts University

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Decluttering can be stressful − a clinical psychologist explains how personal values can make it easier

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theconversation.com – Mary E. Dozier, Assistant Professor of Psychology, Mississippi State University – 2025-02-11 07:47:00

Decluttering can be stressful − a clinical psychologist explains how personal values can make it easier

Asking how discarding an item fits with a person’s goals can help them decide whether to keep it.
MoMo Productions via Getty Images

Mary E. Dozier, Mississippi State University

I recently helped my mom sort through boxes she inherited when my grandparents passed away. One box was labeled – either ironically or genuinely – “toothpick holders and other treasures.” Inside were many keepsakes from moments now lost to history – although we found no toothpick holders.

My favorite of the items we sorted through was a solitary puzzle piece, an artifact reflecting my late grandmother’s penchant for hiding the final piece to a jigsaw puzzle just to swoop in at the last moment and finish it.

After several hours of reminiscing, my mom and I threw away 90% of what we had sorted.

“Why did I keep this?” is a question I hear frequently, both from my family and friends and from patients. I am a licensed clinical psychologist whose research focuses on the characterization, assessment and treatment of hoarding disorder, particularly for adults 60 years of age or older. As such, I spend a great deal of my time thinking about this question.

What drives the need to keep stuff?

Hoarding disorder is a psychiatric condition defined by urges to save items and difficulty discarding current possessions. For adults with “clinically severe” hoarding disorder, this leads to a level of household clutter that impairs daily functioning and can even create a fire hazard. In my professional experience, however, many adults struggle with clutter even if they do not meet the clinical criteria for hoarding disorder.

Holding on to things that have sentimental value or could be useful in the future is a natural part of growing older. For some people, though, this tendency to hold on to objects grows over time, to the point that they eventually do meet criteria for hoarding disorder. Age-related changes in executive function may help explain the increase in prevalence of hoarding disorder as we get older; increasing difficulty with decision-making in general also affects decisions around household clutter.

The traditional model behind hoarding disorder suggests that difficulty with discarding comes from distress during decision-making. However, my research shows that this may be less true of older adults.

A room full of piles of papers, stacked shelves and a tricycle.
Time to declutter.
Kurt Whitman/Education Images via Getty Images

When I was a graduate student, I conducted a study in which we asked adults with hoarding disorder to spend 15 minutes making decisions about whether to keep or discard various items brought from their home. Participants could sort whatever items they wanted. Most chose to sort paper items such as old mail, cards or notes.

We found that age was associated with lower levels of distress during the task, such that participants who were older tended to feel less stressed when making the decision about what to keep and what to discard. We also found that many participants, particularly those who were older, actually reported positive emotions while sorting their items.

In new research publishing soon, my current team replicated this finding using a home-based version of the task. This suggests that fear of making the wrong decision isn’t a universal driver of our urge to save items.

In fact, a study my team published in August 2024 with adults over 50 with hoarding disorder suggests that altruism, a personality trait of wanting to help others, may explain why some people keep items that others might discard. My colleagues and I compared our participants’ personality profiles with that of adults in the general population of the same gender and age group. Compared with the general population, participants with hoarding disorder scored almost universally high on altruism.

Altruism also comes up frequently in my clinical work with older adults who struggle with clutter. People in our studies often tell me that they have held onto something out of a sense of responsibility, either for the item itself or to the environment.

“I need it to go to a good home” and “my grandmother gave this to me” are sentiments we commonly hear. Thus, people may keep things not out of fear of losing them but because saving them is consistent with their values.

YouTube video
Your values can help guide which possessions should stay in your life and which ones should go.

Leaning into values

In a 2024 study, my team demonstrated that taking a values-based approach to decluttering helps older adults to decrease household clutter and increases their positive affect, a state of mind characterized by feelings such as joy and contentment. Clinicians visited the homes of older adults with hoarding disorder for one hour per week for six weeks. At each visit, the clinicians used a technique called motivational interviewing to help participants talk through their decisions while they sorted household clutter.

We found that having participants start with identifying their values allowed them to maintain focus on their long-term goals. Too often, people focus on the immediate ability of an object to “spark joy” and forget to consider whether an object has greater meaning and purpose. Values are the abstract beliefs that we humans use to create our goals. Values are whatever drives us and can include family, faith or frivolity.

Because values are subjective, what people identify as important to keep is also subjective. For example, the dress I wore to my sister’s wedding reminded me of a wonderful day. However, when it no longer fit I gave it away because doing so was more consistent with my values of utility and helpfulness: I wanted the dress to go to someone who needed it and would use it. Someone who more strongly valued family and beauty might have prioritized keeping the dress because of the aesthetics and its link to a family event.

Additionally, we found that instead of challenging the reasons a person might have for keeping an item, it is helpful to instead focus on eliciting their reasons for discarding it and the goals they have for their home and their life.

Tips for sweeping away the old

My research on using motivational interviewing for decluttering and my observations from a current clinical trial on the approach point to some practical steps people can take to declutter their home. Although my work has been primarily with older adults, these tips should be helpful for people of all ages.

Start with writing out your values. Every object in your home should feel value-consistent for you. For example, if tradition and faith are important values for you, you might be more inclined to hold onto a cookbook that was made by the elders at your church and more able to let go of a cookbook you picked up on a whim at a bookstore.

If, instead, health and creativity are your core values, it might be more important to hold onto a cookbook of novel ways to sneak more vegetables into your diet.

Defining value-consistent goals for using your space can help to maintain motivation as you declutter. Are you clearing off your desk so you can work more efficiently? Making space on kitchen counters to bake cookies with your grandchildren?

Remember that sometimes your values will conflict. At those moments, it may help to reflect on whether keeping or discarding an object will bring you closer to your goals for the space.

Similarly, remember that values are subjective. If you are helping a loved one declutter, maintain a curious, nonjudgmental attitude. Where you might see a box filled with junk, your grandmother might see something filled with “toothpick holders and other treasures.”

For additional resources and information on hoarding disorder, visit the International OCD Foundation website.The Conversation

Mary E. Dozier, Assistant Professor of Psychology, Mississippi State University

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Why are migrants dying trying to cross into the US? These are the 3 main risks they face

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theconversation.com – Marni LaFleur, Assistant Professor of Anthropology, University of San Diego – 2025-02-11 07:46:00

Why are migrants dying trying to cross into the US? These are the 3 main risks they face

An altar set at the U.S.-Mexico border wall in Baja, Calif., in November 2024 honors migrants who died trying to reach the U.S.
Guillermo Arias/AFP via Getty Images

Marni LaFleur, University of San Diego

President Donald Trump closed much of the activity at the U.S.-Mexico border in January 2025, making it impossible for migrants who arrive at a U.S. port of entry to apply for asylum. Trump’s border policies are likely to make it far more difficult and dangerous for migrants trying to reach the U.S. – but won’t deter all people who want to cross the U.S.-Mexico border without legal authorization.

The number of migrants crossing from Mexico into the U.S. without legal authorization dropped dramatically in 2024. But for a long time, crossing the U.S.-Mexico border by land has been the world’s deadliest migration route.

U.S. Customs and Border Protection recovered the remains of 10,784 migrants from 1988 through 2024.

This figure is an estimate of the total number of migrants who have died trying to cross from Mexico into the U.S. – there is no centralized system or organization that tracks migrant deaths, or any federal laws guiding authorities on how to manage the remains of migrants.

Many other dead migrants are also never found.

I am a professor of anthropology and have spent the past several years trying to understand how and why migrants die trying to enter the U.S.

Stranded migrants who are now staying in Mexican border towns and others with plans to still try to illegally cross into the U.S. might pursue increasingly dangerous ways to enter the country.

Research shows that there are three main reasons why migrants die trying to reach the U.S. from Mexico. First, migrants are often exposed to extreme weather conditions. Second, they drown in rivers or other bodies of water. Third, they could also experience blunt force trauma because of falls or motor vehicle accidents.

A white-and-green pickup truck is at the top of a river bank. Near the river is a body lying face down.
A body of a man is found by the Rio Grande in Ciudad Juarez, Mexico, on March 28, 2024.
David Peinado/Anadolu via Getty Images

Environmental exposure is common and dangerous

Migrants coming from Central and South America often travel to the U.S. in groups, typically with the help of a guide, called a coyote, they pay to help them.

They may spend days or weeks walking through remote areas without access to shelter or fresh food and clean water. They might sleep outdoors in very cold weather and walk during extreme heat. This can cause hypothermia or hyperthermia.

One of those remote areas is the Sonoran Desert, which spans the southwest U.S. into northwest Mexico. It is divided by the U.S.-Mexico border and is one of the hottest places on Earth. Ambient temperatures can soar to or above 118 degrees Fahrenheit, or 48 degrees Celsius.

As part of the strategy to stop migrants from coming to the U.S., Customs and Border Protection does not place many officers in the depths of the desert along the border. The government’s 1994 migration “prevention through deterrence” strategy explains that because the desert itself poses mortal danger to individuals, it is unnecessary to guard the land.

With border barriers, video surveillance, bright lights and many patrol agents closer to more populated areas along the U.S.-Mexico border, migrants can view the desert as a viable alternative for entering the U.S. Deterrent practices have been found to not stop migrants from trying to enter the U.S., but they do increase the number of migrants who die trying to do so.

Even migrants who are near help or are rescued from the desert may not recover from exposure to extreme temperatures. In 2023, for example, a 9-year-old migrant boy died from organ failure after authorities found him along the Arizona border.

Drowning poses another risk

Drowning is another leading cause of death for migrants trying to reach the U.S.

In California, for example, the 82-mile-long All-American Canal runs parallel to the U.S.-Mexico border. Although the canal doesn’t look particularly dangerous, it is deep, cold, fast-moving and has steep concrete edges that are difficult to scale. Migrants might not be able to swim, or others, particularly women and children, are not strong enough to withstand the force of the currents.

Areas of the Rio Grande, a river that divides the U.S. and Mexico in some areas of Texas, have become hot spots for migrant drownings. Approximately 1,107 migrants died trying to cross this river between 2017 to 2023. The river is fast and deep and is filled with rocks and heavy vegetation that make crossing difficult.

Additionally, in an effort to further deter migrant crossing at Eagle Pass, an area of the Rio Grande, the Texas National Guard installed more than 100 miles of razor wire along the river’s banks in 2024. They set up a large string of oversized orange buoys in the water, creating what the federal government called a navigation obstruction for migrants.

These tactics have sparked larger debates on how to handle migration, and which government agency is responsible for preventing people from crossing into the country, or apprehending them when they do so.

In 2024, a Mexican woman and her two children tried to cross the Rio Grande but struggled to do so. As Customs and Border Protection agents prepared to rescue the distressed and drowning individuals, the Texas National Guard prevented rescue attempts. The family died from drowning, and their bodies were later recovered.

Blunt force trauma

Another leading cause of death of migrants is falling from heights or experiencing car accidents.

At the California border region alone, approximately 20% of migrant deaths were due to blunt force trauma between 2018 through 2023. This rate rose after the 2020 expansion of the border wall, which now spans 741 miles of the U.S.-Mexico border. In total, the border is nearly 2,000 miles.

In one incident in Texas in 2020, a pregnant 19-year-old Guatemalan woman died after falling from the border wall, which ranges from 18 to 30 feet. Medical authorities were unable to save the fetus.

In Texas, between 2021 and 2023, high-speed chases by immigration officials led to the deaths of 74 people. Some individuals were ejected from moving vehicles, while others were hit by fast-moving vehicles. Another particularly deadly accident occurred in 2021 in Holtville, California, when an SUV transporting 25 migrants collided with a semitruck. Thirteen migrants were killed.

A woman wrapped in a foil blanket sleeps on the floor next to a child, surrounded by dry shrubs.
Migrants from Colombia sleep outside in Jacumba, Calif., after crossing into the U.S. in May 2023.
Gregory Bull/Associated Press

‘Prevention through deterrence’

For more than 30 years, the U.S. government has tried to prevent migrants from reaching the U.S. through different strategies, like deploying Border Patrol agents or building walls.

There are many practical and policy-based interventions that would make it safer for migrants to cross through the U.S. and Mexico deserts. For example, water stations along known migration routes of the desert save lives.

Regardless of how the Trump administration tries to stop migrants from reaching the U.S., people will likely still try to come and embark on unsafe journeys to do so – and I will continue to track their experiences and deaths.The Conversation

Marni LaFleur, Assistant Professor of Anthropology, University of San Diego

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