Android CardView със странна рамка, когато е прозрачен

Имам проблеми с прозрачността на CardView и card_elevation. Опитвайки се да използвам прозрачен CardView, резултатът е:

Без прозрачност:

Това, което се опитвам да получа, е нещо подобно:

Ето моят xml:

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@mipmap/eifell"
    android:padding="10dp"
    tools:context=".MainActivity">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:paddingTop="5dp"
        android:background="@android:color/transparent">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">

            <android.support.v7.widget.CardView
                android:id="@+id/newsCardView"
                android:layout_width="match_parent"
                android:layout_height="175dp"
                card_view:cardBackgroundColor="#602B608A"
                card_view:cardElevation="5dp">

                <LinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="match_parent"
                    android:background="@android:color/transparent">
                </LinearLayout>

            </android.support.v7.widget.CardView>

        </LinearLayout>
    </ScrollView>

</RelativeLayout>